Ultrasound diagnosis of kidney diseases. Anatomy of the kidneys and. Difficulties and errors in ultrasound and x-ray diagnostics of renal pseudotumors Fetal lobulation of the kidney

The renal pyramids are the specific areas through which urine enters the collecting system after fluid is filtered from the bloodstream through tubular systems. Already from the penis, urine moves through the ureter and enters the bladder. Disorders of the pyramids can be observed in one or both kidneys, which leads to dysfunction of the organ and requires mandatory treatment. Pathological changes are detected through ultrasound and only after examination and diagnosis, the doctor prescribes the necessary therapy.

What does hyperechogenicity of pyramids mean?

The pyramids of the kidneys are certain areas through which urine enters the collecting system after filtering fluid from the bloodstream.

The normal healthy state of the kidneys means the correct shape, uniformity of structure, symmetrical location, and at the same time, ultrasound waves are not reflected on the echogram - a study carried out when a disease is suspected. Pathologies change the structure and appearance of the kidneys and have special characteristics that indicate the severity of the disease and the state of the inclusions.

For example, organs can be asymmetrically enlarged/reduced, have internal degenerative changes in parenchymal tissue - all this leads to poor penetration of the ultrasonic wave. In addition, echogenicity is impaired due to the presence of stones and sand in the kidney.

Important! Echogenicity is the ability of wave reflection of sound from a solid or liquid substance. All organs are echogenic, which makes it possible to do ultrasound. Hyperechogenicity is a reflection of increased strength, revealing inclusions in organs. Based on the monitor readings, the specialist identifies the presence of an acoustic shadow, which is a determining factor in the inclusion density. Thus, if the kidneys and pyramids are healthy, the study will not show any wave abnormalities

Symptoms of hyperechogenicity

Syndrome of hyperechoic renal pyramids causes pain in the lower back of a cutting, stabbing nature

Hyperechoic renal pyramid syndrome has a number of symptoms:

Body temperature changes;
Pain in the lower back of a cutting, stabbing nature;
Changes in the color and smell of urine, sometimes blood droplets are observed;
Abnormal stool;
Nausea, vomiting.

The syndrome and symptoms indicate a clear kidney disease that needs to be treated. The release of pyramids can be caused by various organ diseases: nephritis, nephrosis, neoplasms and tumors. Additional diagnostics, examination by a doctor and laboratory tests are required to establish the underlying disease. After which the specialist prescribes therapeutic treatment measures.

Types of hyperechoic inclusions

All formations are divided into three types, based on what picture is visible on ultrasound

All formations are divided into three types, based on what picture is visible on ultrasound:

A large inclusion with an acoustic shadow most often indicates the presence of stones, focal inflammation, and disorders of the lymphatic system;

A large formation without a shadow can be caused by cysts, fatty layers in the sinuses of the kidneys, tumors of various types or small stones;

Small inclusions without a shadow are microcalcicates, psammoma bodies.

Possible diseases depending on the size of inclusions:

Urolithiasis or inflammation - manifests itself as large echogenic inclusions.

Single inclusions without a shadow indicate:

hematomas;
sclerotic changes in blood vessels;
sand and small stones;
scarring of organ tissue, for example, parenchymal tissue, where scarring occurred due to untreated diseases;
fatty seals in the sinuses of the kidneys;
cystosis, tumors, neoplasms.

Important! If the device monitor shows obvious sparkles without shadows, then in the kidneys there may be an accumulation of compounds (psammoma) of a protein-fatty nature, framed by calcium salts or calcifications. It is not recommended to ignore this symptom, as this may be the beginning of the development of malignant tumors. In particular, oncological formations include calcifications in 30% and psammonic bodies in 50%.

Inclusions of the echo complex of the kidneys on ultrasound are a study that allows us to identify abnormal developments of all parts of the organ, the dynamics of diseases and parenchymal changes. Depending on the echogenic indicators, the characteristics of the disease are determined, therapeutic and other treatment is selected.

As for the symptoms, even knowing about the pyramids in the kidneys, what they are, what pathologies are indicated by changes in structure and echogenicity, the invisibility of signs of the disease often does not cause concern. Patients put up with the pain and delay their visit to the doctor. It is categorically not recommended to do this: if the disease has affected the pyramids, it means that the pathological changes have gone far enough and can turn into not only purulent inflammatory processes, but also chronic diseases, the treatment of which will require a lot of time and money.

Source

03-med.info

Structure and purpose of parenchyma

Under the capsule lie several layers of dense parenchyma, differing both in color and consistency - in accordance with the presence of structures in them that allow the organ to perform the tasks facing the organ.

In addition to its most well-known purpose - to be part of the excretory (excretory) system, the kidney also performs the functions of an organ:

endocrine (intrasecretory);
osmo- and ion-regulating;
participating in the body both in general metabolism (metabolism) and in hematopoiesis - in particular.

This means that the kidney not only filters the blood, but also regulates its salt composition, maintains the optimal water content for the body’s needs, affects the level of blood pressure, and in addition produces erythropoietin (a biologically active substance that regulates the rate of red blood cell formation) .

Cortical and medulla layers

According to the generally accepted position, the two layers of the kidney are called:

cortical;
cerebral.

The layer lying directly under the dense elastic capsule, the outermost in relation to the center of the organ, the densest and most lightly colored, is called the cortical layer, while the layer located below it, darker and closer to the center, is the medulla layer.

A fresh longitudinal section reveals even to the naked eye the heterogeneity of the structure of the renal tissues: it shows radial striations - structures of the medulla, semicircular tongues pressing into the cortical substance, as well as red dots of the renal corpuscles-nephrons.

With purely external solidity, the kidney is characterized by lobulation, due to the existence of pyramids, delimited from each other by natural structures - renal columns formed by the cortex, dividing the medulla into lobes.

Glomeruli and urine formation

To allow purification (filtration) of blood in the kidney, there are zones of direct natural contact of vascular formations with tubular (hollow) structures, the structure of which allows the use of the laws of osmosis and hydrodynamic (arising as a result of fluid flow) pressure. These are nephrons, the arterial system of which forms several capillary networks.

The first is a capillary glomerulus, completely immersed in a cup-shaped depression in the center of the flask-shaped expanded primary element of the nephron - the Shumlyansky-Bowman capsule.

The outer surface of the capillaries, consisting of a single layer of endothelial cells, is almost completely covered with intimately tightly adjacent cytopodia. These are numerous stalk-like processes that originate from the centrally passing cytotrabecula, which in turn is a process of the podocyte cell.

They arise as a result of the entry of the “legs” of some podocytes into the spaces between the same processes of other, neighboring cells, forming a structure reminiscent of a zipper lock.

The narrowness of the filtration slits (or slit diaphragms), determined by the degree of contraction of the podocyte “feet”, serves as a purely mechanical obstacle for large molecules, preventing them from leaving the capillary bed.

The second wonderful mechanism that ensures the fineness of filtration is the presence on the surface of the slit diaphragms of proteins that have an electrical charge of the same name as the charge of the molecules approaching them in the composition of the filtered blood. This electrical “curtain” also prevents unwanted components from entering the primary urine.

The mechanism of formation of secondary urine in other parts of the renal tubule is due to the presence of osmotic pressure directed from the capillaries into the lumen of the tubule, braided by these capillaries until their walls “stick” to each other.

Parenchyma thickness at different ages

Due to the onset of age-related changes, tissue atrophy occurs with thinning of both the cortical and medulla layers. If at a young age the thickness of the parenchyma is from 1.5 to 2.5 cm, then upon reaching 60 years or more it thins out to 1.1 cm, leading to a decrease in the size of the kidney (its wrinkling, usually on both sides).

Atrophic processes in the kidneys are associated both with maintaining a certain lifestyle and with the progression of diseases acquired during life.

Conditions that cause a decrease in the volume and mass of renal tissue are caused by both general vascular diseases of the sclerosing type and the loss of the ability of the renal structures to perform their functions due to:

voluntary chronic intoxication;
sedentary lifestyle;
the nature of the activity associated with stress and occupational hazards;
living in a certain climate.

Column Bertini

Also called Bertinian columns, or renal columns, or Bertin's columns, these beam-shaped strands of connective tissue, passing between the pyramids of the kidney from the cortex to the medulla, divide the organ into lobes in the most natural way.

Because inside each of them there are blood vessels that ensure metabolism in the organ - the renal artery and vein, at this level of their branching they are called interlobar (and at the next - lobular).

Thus, the presence of Bertin's columns, which differ in a longitudinal section from the pyramids by a completely different structure (with the presence of sections of tubules passing in different directions), allows for communication between all zones and formations of the renal parenchyma.

Despite the possibility of the existence of a fully formed pyramid inside the particularly powerful column of Bertin, the same intensity of the vascular pattern in it and in the cortical layer of the parenchyma indicates their common origin and purpose.

Parenchymal bridge

A kidney is an organ that can take any shape: from the classic bean-shaped to a horseshoe-shaped or even more unusual.

Sometimes an ultrasound of an organ reveals the presence of a parenchymal bridge in it - a connective tissue retraction, which, starting on its dorsal (posterior) surface, reaches the level of the median renal complex, as if dividing the kidney crosswise into two more or less equal “half-beans”. This phenomenon is explained by too strong wedging of Bertin's columns into the kidney cavity.

Despite the apparent unnaturalness of this appearance of the organ and the absence of involvement of its vascular and filtering structures, this structure is considered a variant of the norm (pseudopathology) and is not an indication for surgical treatment, just like the presence of a parenchymal constriction dividing the renal sinus into two seemingly separate parts, but without complete doubling of the pelvis.

Regeneration ability

Regeneration of the kidney parenchyma is not only possible, but also safely carried out by the organ in the presence of certain conditions, which has been proven by many years of observation of patients who have suffered glomerulonephritis - an infectious-allergic-toxic kidney disease with massive damage to the renal corpuscles (nephrons).

Studies have shown that restoration of organ function occurs not through the creation of new ones, but through the mobilization of already existing nephrons, which were previously in a conserved state. Their blood supply remained sufficient solely to maintain minimal vital activity.

But activation of neurohumoral regulation after the subsidence of the acute inflammatory process led to the restoration of microcirculation in areas where the renal tissue was not subject to diffuse sclerosis.

These observations suggest that the key to the possibility of regeneration of the renal parenchyma is the ability to restore blood supply in areas where it has been significantly reduced for any reason.

Diffuse changes and echogenicity

In addition to glomerulonephritis, there are other diseases that can lead to the appearance of focal atrophy of the renal tissue, which has varying degrees of extent, called by the medical term: diffuse changes in the structure of the kidneys.

These are all diseases and conditions that lead to sclerosis of blood vessels.

The list can begin with infectious processes in the body (flu, streptococcal infection) and chronic (habitual household) intoxications: drinking alcohol, smoking.

It is completed by production and service-related hazards (in the form of work in an electrochemical, galvanic workshop, activities with regular contact with highly toxic compounds of lead and mercury, as well as those associated with exposure to high-frequency electromagnetic and ionizing radiation).

The concept of echogenicity implies the heterogeneity of the structure of an organ with varying degrees of permeability of its individual zones for ultrasound examination (ultrasound).

Just as the density of different tissues is different for “translation” with X-rays, on the path of the ultrasound beam there are also both hollow formations and areas with high tissue density, depending on which the ultrasound picture will differ in great variety, giving an idea of the internal structure organ.

As a result, the ultrasound method is a truly unique and valuable diagnostic study that cannot be replaced by any other, allowing to give a complete picture of the structure and function of the kidneys without resorting to an autopsy or other traumatic actions towards the patient.

Also, the outstanding ability to recover in case of damage can significantly regulate the lifespan of the organ (both by saving it by the kidney owner himself, and by providing medical care in cases requiring intervention).

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Hyperechoic renal pyramid syndrome

If long-term, then chronic renal failure, if acute, then acute renal failure. Poisoning can cause both. The kidneys play an important role in the human body, and their normal functionality affects overall health. Therefore, when the first signs of illness appear, it is recommended to immediately provide the necessary assistance to the kidneys.

Characteristic symptoms that cause kidney problems

If these symptoms appear, it is important to immediately contact your doctor, who will prescribe an immediate examination and the necessary tests. Also, these symptoms may indicate that the patient has one kidney larger than the other, so it is necessary to undergo additional examination, including renal clearance. If, after hypothermia, a person’s kidneys begin to hurt, only one conclusion can be drawn - this means that the development of the inflammatory process began earlier.

Symptoms Associated with Kidney Disease

A person can get closed kidney injuries in car accidents, falling from a height, and even while playing sports. Each of these types of diseases has its own dangers, so in no case should you experiment on yourself or self-medicate. Often, patients who actually have a kidney carbuncle end up in the hospital with completely different diagnoses.

Types of hyperechoic inclusions and diagnosis

With this disease, pus is also released, so it is very dangerous and requires immediate hospitalization of the patient in a medical facility. It has been proven that dietary nutrition has a very beneficial effect on many kidney diseases and allows them to work in a gentle manner.

The kidneys are a paired organ and perform several functions in the human body simultaneously. Therefore, during a diagnostic ultrasound examination, a mandatory examination of both kidneys is carried out. Dysfunction may begin on one side and affect the other. Hyperechoic inclusions in the kidneys can be observed in either one or two. The location of inclusions is very diverse and depends on predisposing unfavorable factors.

Website about kidney diseases

Pathological processes of various etiologies change the structure and appearance of the kidneys depending on the severity of the disease and the state of the inclusions. Hyperechogenicity means extremely strong reflection, indicating the presence of any inclusions in the kidneys. There are several types of echogenic inclusions, which are used to determine the pathological condition of the kidneys. Hyperechoic inclusions are divided into two large groups: stones (sand) and neoplasms.

Large inclusions in the kidneys. This can also be confirmed by the presence of calcifications and psammoma bodies in the tumor, as well as sclerotic areas. During the examination, several different types of echogenic inclusions may be detected. Impaired kidney function is always accompanied by weakness and fatigue. This condition is inherent in the acute development of diseases or the exacerbation phase of chronic pathological processes in the kidneys.

Therapeutic measures and prevention

It is necessary to evaluate the condition of the kidney parenchyma against the background of prominent pyramids. Depending on the severity of the condition and the type of pathological process, treatment can be therapeutic or surgical.

Pyelonephritis is an inflammatory process that occurs only in the pyelocaliceal system of the kidney and is accompanied by pronounced laboratory changes. Rice. 1 Visualization of the right kidney. The sensor is located in the posterior axillary line on the right.

Necessary treatment

Clinical manifestations

The left kidney is also located in a kind of triangle, the sides of which are the spine, muscles and spleen. The sonographic characteristics of the renal capsule and parenchyma of the normal kidney are generally accepted.

Partial or complete rupture of the collecting system image at the same location indicates a duplex kidney with separate ureters and blood supply for each half.

Kidney dystopia is an anomaly of kidney development in which the kidney does not rise to its normal level during embryogenesis. In this case, variants of heterolateral dystopia with and without fusion of the kidneys are possible. When echographic detection of an abnormally located kidney, difficulties usually arise in the differential diagnosis of nephroptosis and dystopia. It must be remembered that a kidney with nephroptosis has a normal length ureter and a vascular pedicle located at the usual level (level L1-L2 of the lumbar vertebrae).

As for the increased echogenicity of the parenchyma and prominent pyramids, the reasons for this condition may be different. In newborns, the structure and condition of the pyramids themselves and the fluids released through them are assessed. The base of the triangle is the boundary between the cortex and the pyramid along the periphery of the cut of the pyramid. The syndrome itself is not life-threatening and is a symptom of a disease that is determined after a full comprehensive examination.

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Concepts - hyperechogenicity and acoustic shadow?

Echogenicity is the ability of bodies of liquid and solid consistency to reflect ultrasonic waves. All organs located inside a person are echogenic, which is what allows ultrasound examination. Ultrasound helps to study the activity of the kidneys, determine their integrity and confirm or exclude the presence of neoplasms of a malignant or benign nature. In a healthy person, the organ is round in shape with a symmetrical location and inability to reflect sound waves. In cases of pathologies, the size of the kidneys changes, the location becomes asymmetrical and inclusions appear that can deflect sound waves.

On ultrasound, hyperechoic inclusions appear as white spots.

The word “hyper” refers to the increased ability of echogenic tissues to reflect ultrasound waves. During an ultrasound, the specialist sees white spots on the screen and determines whether they have an acoustic shadow, or more precisely, an accumulation of ultrasonic waves that did not pass through it. Waves have a much higher density than air, so they cannot pass exclusively through a dense object. Hyperechogenicity is not a separate disease, but a symptom that indicates the appearance of various kinds of pathologies inside the kidneys.

Anomalies of relationship (fused kidneys)

With this anomaly, the kidneys can be fused symmetrically or asymmetrically.

Symmetrical forms of fusion (fusion occurs at the same poles - lower or upper) include horseshoe-shaped and biscuit-shaped buds.

Horseshoe kidney

In our observations, it was detected in 0.2% of patients, and in most cases in boys. Echodiagnosis presents certain difficulties, which increase when this anomaly is combined with various diseases (hydronephrosis, cysts, polycystic disease, hematomas, paranephritis, tumors, injuries).

An unaffected horseshoe kidney is always located lower than a normal kidney, has a large size, but never gains the sum of two normal renal sizes, the zone of parenchyma and the collecting system is well demarcated. Visualization and differentiation are improved by applying aqueous pressure, which allows for good differentiation of dilated pelvises. It should be noted that echographically it is very difficult to determine which poles the kidneys are fused with, except in cases where, when viewed through the anterior abdominal wall, it is possible to locate the adrenal glands at opposite poles, and then this is only possible with an anomaly of the left kidney.

Biscuit bud

This anomaly is very rare and is formed as a result of the uniform action of the forces of the small intestine during the period of movement of the kidneys from the pelvis to the lumbar region. When they are retained in the pelvis, fusion occurs along the entire length. The kidney is located low in the pelvis as a flat-oval-elongated formation with clear contours, delimiting the zone of parenchyma and the collecting system without differentiating the site of fusion. May be mistaken for a tumor. Echodiagnosis of a biscuit-shaped kidney is difficult when combined with various diseases. Priority goes to excretory urography.

Asymmetric forms of fusion include kidneys fused in the form of the Latin letters S, I and L. With this anomaly, the kidneys are fused with opposite poles due to the uneven impact of the forces of the small intestine during their movement from the pelvis to the lumbar region. The longitudinal axes of S and 1-shaped fused buds are parallel. The S-shaped kidney is located in the pelvis in a horizontal or oblique position, and the I-shaped kidney is located vertically and parallel to the inferior vena cava and the abdominal aorta.

With an L-shaped kidney, the longitudinal axes are perpendicular and are located in the pelvis in a horizontal position. It should be noted that this anomaly can easily be confused with a horseshoe kidney. Typically, abnormal kidneys have clear contours with a well-differentiated zone of parenchyma and often zones of two pyelocaliceal systems. Sometimes, with an S-shaped kidney, it is possible to identify the isthmus (fusion site). Despite the fact that echography reveals the presence of abnormal kidneys, excretory urography takes priority in their differential diagnosis.

Quantity anomalies

Double kidney

The most common abnormality in the number of kidneys (approximately 4%) is kidney duplication, which can be unilateral or bilateral, complete or incomplete.

Paired kidney

With complete duplication, there are two collecting systems - two pelvis, two ureters and two vascular bundles. The echogram clearly shows the pelvis, the beginning of the ureters, and sometimes it is possible to identify vascular bundles.

An incompletely duplicated kidney differs from a complete one in that it is fed by one vascular bundle. The ureter can be doubled at the top and enter the bladder with one or two orifices. On the echogram, the double kidney looks elongated and there is a characteristic sign of separation of the zones of the parenchyma and the collecting system.

Difficulties in echographic differentiation arise with pyelonephritis, hydronephrosis, urolithiasis and tumors of one of the halves of a double kidney. The full anatomical picture of a double kidney can only be seen radiographically.

This pathology is extremely rare. Paired buds can be one- or two-sided, identical or different in size. According to our data (there is no description of this pathology in the available literature), a unilateral paired kidney was identified in 5 women aged 19-34 years and a bilateral one in 2 pregnant women aged 21 and 28 years. In 6 out of 7 cases that we identified, the paired kidneys were of the same size, on average 8.2-3.6 cm. The width of the kidney was taken as only 1/2 the width of the parenchyma zone in the fused part of the kidneys.

A characteristic feature is their longitudinal fusion with lateral surfaces. The echostructure of paired kidneys does not differ from that of a normal kidney, that is, the zones of the parenchyma and the pyelocaliceal system are very clearly distinguished. A special feature is that the width of the parenchyma zone at the site of fusion does not exceed the value in the non-fused part of the kidneys. Based on the echo picture, it can be assumed that fusion occurs at the level of the entire thickness of the parenchyma of both kidneys. The option of complete longitudinal doubling of the kidney is not excluded. The ureters behave in the same way as with a complete double kidney.

Abnormality of the renal parenchyma

Abnormalities of the renal parenchyma include agenesis, aplasia, hypoplastic kidney, accessory (third) kidney, additional lobule and cystic parenchymal anomalies - polycystic, multicystic, solitary cyst, multilocular cyst, spongy kidney, megacalycosis and calyx diverticulum.

Agenesis

Congenital absence of one or both kidneys. With unilateral agenesis, the specific structure of the kidney is not located on this side, but sometimes it is possible to locate an enlarged adrenal gland. On the opposite side, a hypertrophied kidney, defective in echo structure, is located.

However, it should be remembered that the absence of a kidney in an anatomical location does not indicate the presence of agenesis. The final diagnosis can be made only after detailed echographic and radiological studies. Bilateral agenesis is very rare and is diagnosed in the fetus in the second and third periods of pregnancy, when all organs are developed. However, a thorough echographic examination does not reveal the echostructure of the kidneys and bladder. The study is difficult to carry out, since with this anomaly there is always oligohydramnios. Fetuses with this anomaly are born dead.

Aplasia

Profound underdevelopment of the renal parenchyma with frequent cases of absence of the ureter. It can be one-sided or two-sided.

With unilateral aplasia, there is no specificity of the kidney structure and an oval-elongated formation with unclear erased contours, heterochoic (of different acoustic densities) is located, although small cysts and calcifications can be located. It is not clinically manifested and is an echographic finding when examining the kidneys.

Bilateral aplasia is extremely rare. In this case, the fetus cannot be imaged of the kidneys and bladder.

Hypoplastic kidney

Congenital reduction in kidney size. On the echogram, the kidney is reduced in size (on average, its length is 5.2 cm, width - 2.4 cm), the zones of the parenchyma and the collecting system are narrowed, but the specificity of the structure of these zones is preserved.

In 3 patients, we observed a dwarf kidney measuring 3-2 cm. The contours of the kidney were blurred, the parenchyma was heterogeneous in echogenicity; There is no division into zones.

It should be remembered that it can be very difficult to distinguish a hypoplastic kidney from a wrinkled kidney, in which the size is also reduced, but the latter has blurred contours and division into zones; such a kidney is poorly demarcated from the tissues surrounding it.

Accessory (third) kidney

It is extremely rare. We identified 2 cases. The accessory kidney is usually located below the main one and may be slightly smaller than it. In our cases, the main and accessory kidneys were located in a horizontal plane and had the same dimensions, but slightly smaller than the generally accepted average values for this age (7.1-2.8 cm). The parenchyma and pyelocaliceal system in both kidneys are clearly visible. The ureter of the accessory kidney can empty into the main ureter or independently into the bladder.

There can be one (or several) additional lobule of one of the kidneys and is most often located at the poles, located as a small oval formation with clear contours; the echostructure of the lobules is similar to that of the tissue of the main kidney. Sometimes additional lobules can be easily mistaken for the adrenal gland, although their echo structure is somewhat different, sometimes they can be confused with a space-occupying formation growing exophytically.

Anatomical variations of the normally functioning kidney

There are anatomical variations in the structure of the parenchyma and pyelocaliceal system of the kidney. It should be immediately noted that they have no clinical significance, however, some of them may pose diagnostic problems for the researcher.

A parenchymal defect is rare and is located in the form of an echogenic zone of a triangular shape, the base of which is connected with the fibrous capsule, and the apex with the wall of the renal sinus.

Kidney with an oval-convex uneven outer contour

Happens quite often. It is characterized by isolated hypertrophy (bulging in the form of a hump) of the parenchyma towards the outer edge of the middle third of the kidney. An inexperienced specialist may mistake it for a tumor with exophytic growth or a carbuncle (with the latter there is an acute clinical picture).

Uneven lobulated kidney

Usually occurs in children under 2-3 years of age. Rarely does this phase of embryonic structure persist into adults. It is characterized by a uniform division into 3-4 zones of low echogenicity protruding on the outer surface (parenchyma of the lobules).

Kidney with an isolated zone of parenchymal hypertrophy inward

This anomaly of the parenchyma is quite common; it is characterized by isolated hypertrophy and protrusions in the form of a pseudopodia between two pyramids up to the pyelocaliceal system, which, in the absence of a clinic, we tend to consider as a variant of the individual norm. It can be mistaken for a tumor, and therefore patients with exophytic and endophytic additional growth of parenchyma should be subjected to invasive research methods.

Polycystic kidney disease

Congenital, always bilateral cystic anomaly of the renal parenchyma.

Before the introduction of echography, especially in real time, the diagnosis of polycystic disease presented great difficulties, since the percentage of correct diagnosis by X-ray methods did not exceed 80. In our observations of more than 600 patients, echographic diagnosis turned out to be correct in 100% of cases. The polycystic kidney is always enlarged in size, the contours are uneven, oval-convex, the echostructure is not differentiated, only strips of parenchyma and many round, different-sized anechoic formations (cysts) are visible, separated by thin echogenic stripes-septa. Sometimes polycystic kidney takes on the appearance of a bunch of grapes. But in most cases, several large cysts, up to 5-6 cm in diameter, are located, surrounded by many small ones. Sometimes, during dynamic observation of the patient, one can observe the disappearance of large cysts and their ruptures.

The study is performed from the back, but visualization of the right kidney is better through the liver. It should be noted that with a significant size of the kidney and the presence of many cysts, sometimes the liver is only partially visible or not visible at all, and it is possible to mistakenly diagnose polycystic liver disease, which is extremely rare.

Multicystic dysplasia

A congenital anomaly, which is often unilateral, since bilateral is incompatible with life. The multicystic kidney is usually large in size, characterized by uneven contours, the parenchyma is not differentiated and is completely replaced by cysts of various sizes, usually 2-3 large ones. For the purpose of differential diagnosis of polycystic and multicystic diseases, X-ray examination methods are used. Multicystic kidney disease is characterized by high obliteration of the ureter.

Solitary cyst

There are congenital and acquired kidney cysts. Congenital cysts are detected in the fetus in the second and third trimesters of pregnancy or more often in childhood. Acquired cysts are detected more often after 40 years. There are single and multiple, but no more than 2-3 in one kidney. They are located as round formations of different sizes: minimum - 0.5 cm, maximum - over 10 cm in diameter. They originate from the kidney parenchyma and have clear contours, are devoid of echo signals, and are located both on the surface and in different parts of the kidney.

It is difficult to clarify the location of the cyst; First of all, this applies to parapelvic cysts located in the area of the renal hilum. In some cases, they are difficult to differentiate from an enlarged pelvis, hydronephrosis, which may have a similar oval shape. In this regard, it should be remembered that in the case of hydronephrosis, echolocation of the kidney in different scans almost always reveals an interruption of the contours of the fluid formation, that is, a connection with the pelvis and the ureteropelvic segment and calyces, whereas with parapelvic cysts, interruption of the contours of the located fluid formation is not observed.

It should be remembered that the right kidney may be overlaid with images of cysts in the right lobe of the liver or the right half of the abdominal cavity, in particular the intestinal mesentery in Crohn's disease or ovary. A cyst of the lower pole of the spleen, the tail of the pancreas, the left half of the abdominal cavity, the left ovary, or fluid in the stomach with poor evacuation can be mistakenly mistaken for a cyst of the left kidney. Such diagnostic errors are unacceptable, because they lead to serious complications, since the approaches for surgical intervention for these pathologies are different. To avoid mistakes, it is necessary to carefully differentiate the contours of the kidney in different echographic scans by changing the position of the body. In doubtful cases, repeated ultrasound examinations and laparoscopy are indicated.

Echography allows for dynamic monitoring of the growth and condition of cysts (suppuration, rupture, resorption). The dynamics of cyst development is of great clinical importance, since their growth is associated with atrophy of the kidney parenchyma, leading to hemodynamic disturbances and arterial hypertension. Echography helps clarify the moment of possible surgical intervention or conservative treatment, and provides conditions for conducting a targeted diagnostic or therapeutic biopsy.

Dermoid cysts

These are congenital single-chamber, rarely multi-chamber, round formations outlined by an echogenic capsule. They can be located in various parts of the body, rarely in the internal organs and very rarely in the kidneys. They are more common in girls in early childhood, although they can also occur in adults, and be an accidental finding. Depending on their content (hair, fat, bone tissue, etc.), the contents of the formation have different echogenicity - part of the cyst can be high, and part - low (fluid). The wall of the dermoid cyst is thickened, has high echogenicity, and sometimes undergoes calcification and is located as a round, highly echogenic ring, clearly visible on x-ray. It should be noted that sometimes a dermond cyst is echographically difficult to distinguish from a chronic abscess, decay of a cavity and tumor, hypernephroma and Wilms tumor. The diagnosis in such cases can be confirmed by core aspiration biopsy or surgery.

Multilocular cyst

A very rare anomaly (2 cases identified), characterized by the replacement of a section of the renal parenchyma with a multilocular cyst, which is located as a multilocular anechoic formation, separated by narrow echogenic septa. When large sizes are reached, the echo picture is the same as with a multi-chamber hydatid cyst. Differentiation is very difficult. The only distinguishing feature is that an active hydatid cyst grows rapidly compared to a multilocular cyst (the patient’s household usually contains animals that are carriers of echinococcosis).
Males are more often affected. In this case, the kidney can be increased in size; a uniform cystic lesion of the pyramids is characteristic, usually bilateral, without involving the cortex in the pathological process. Cysts are usually small in size, with a diameter of 3 to 5 mm, directed towards the center of the kidney. Although many small cysts can also occur on the surface of the kidney, making it uneven. Many small stones are located in the area of the pyramids. When pyelonephritis is associated, echodiagnosis is difficult.

Megacalycosis (renal calyx dysplasia)

Congenital enlargement of the renal calyces associated with underdevelopment of the renal pyramids. Usually this anomaly is unilateral, although cases of bilateral lesions have been described. In this case, all calyces are affected.

On the echogram, all the calyces are significantly dilated, have a rounded shape, the pelvis, as a rule, if pyelonephritis is not associated, is not dilated, the ureter is freely passable for contrast agent during x-ray examination.

Accumulation of uric acid salts and small stones can be detected. Echography of this pathology can only suggest that the final diagnosis is based on excretory urography and retrograde pyelography, where the cyst cavity, a narrow passage communicating with the renal calyx, is clearly visible.

Calyceal diverticulum

Congenital cystic formation connected to the minor renal calyx through a narrow canal.

Megaureter

Congenital unilateral, less often bilateral segmental expansion along the entire length of the ureter, from 3 mm to 2-3 cm or more, the ureter is located as an anechoic tube of uneven width over a narrowed distal segment.

The length of the ureter can vary from 0.5 to 4-5 cm; the left ureter is most often affected. Megaureter can be primarily obstructive (congenital), secondary obstructive (acquired) due to inflammatory processes, postoperative scars and other reasons, and primarily non-obstructive (idiopathic). Megaureter, especially primarily obstructive, always leads to hydronephrosis and hydrocalycosis.

Ureterocele

One of the rare anomalies of the ureter, arising due to the narrowness of its mouth, in which there is an expansion of all layers of the intramural part of the ureter, protruding in the form of an oval echo-negative formation into the bladder cavity on one or both sides. The cavity of the ureterocele may contain urine - from a few milliliters to the volume of the bladder.

A ureterocele is difficult to differentiate from a diverticulum or hydatid cyst located at the orifice of the ureter.

Early diagnosis of ureterocele is of great importance, as it allows timely relief of the patient from possible dilatation of the upper urinary tract and the development of pyelonephritis and secondary cystitis.

Renal vascular abnormality

This area of pathology for modern echography, even with the use of Doppler, is little or, more precisely, only partially accessible. It only allows us to assume the presence of any vascular pathology when comparing structural changes in the renal parenchyma.

Source: health-medicine.info

- a limited accumulation of pus in the cortex or medulla of the kidney. When computed tomography without contrast, it looks like a formation with unclear contours, containing a liquid component in the center, as well as gas bubbles (if infected with gas-forming flora). The pyogenic membrane has the property of being enhanced by contrast to a significant extent.

Kidney agenesis

- complete absence of the kidney, as well as the ureter, renal arteries and veins on one side.

Kidney adenoma

- a common finding during CT examinations of the retroperitoneal organs. When performing a computed tomography scan of the kidneys (with or without contrast), an adenoma cannot be clearly differentiated from renal cell carcinoma; it looks similar - in the form of a hypo- or hypervascularized node in the renal parenchyma, a heterogeneous - cystic-solid structure, enhancing with contrast.

Angiomyolipoma of the kidney

- a tumor consisting of adipose, muscle and vascular proliferative tissue. On a CT scan of the retroperitoneal space, it looks like a formation of heterogeneous density (areas of low density -20...-60 Hounsfield units against the background of strands of higher, soft tissue density), with uneven edges, deforming the contour of the kidney. Angiomyolipoma is the only kidney tumor whose benign nature can be confirmed without performing any other tests.

Angiomyolipoma of the kidney on computed tomography looks like a rounded formation with heterogeneous density due to the fact that it contains fat, muscle and vascular tissue in different proportions. In the example presented, the average density of the mass near the lower pole of the right kidney is -20 Hounsfield units.

Renal artery aneurysm

- local expansion of the lumen of the renal artery as a result of weakening and stretching of its wall. Diagnosed by CT angiography of the renal artery, the expansion of the lumen is clearly visible, in which blood clots can also be detected.

Kidney aplasia

- reduction in kidney volume and disruption of its normal structure. With aplasia in the kidney, the number of pyramids is less than normal, and the pyelocaliceal complex may have the appearance of an “onion.”

Ureteral atresia

- absence of lumen of the ureter, congenital pathology.

Vesico-ureteral reflux

- a condition in which there is a reverse flow of urine from the bladder into the ureter. This type of reflux can be detected only with retrograde cystography (with filling the bladder with contrast from the outside) by contrasting the distal parts of the ureters.

Kidney cortical substance

- a complex of structures containing renal vessels, tubules and glomeruli. On CT scan of the retroperitoneum, the renal cortex is isodense to the renal medulla; with contrast enhancement, it becomes hyperdense (due to greater vascularization).

On the axial scan, arrows indicate the renal cortex, which appears hyperdense in relation to the medulla in the arterial phase of contrast due to better vascularization.

Kidney medulla

- a structure consisting of renal pyramids separated from each other by the cortex (Bertini's columns). The apices of the pyramids, merging, form the renal papillae, which conduct urine into the pyelocaliceal system.

Bulging of the kidney contour

– with CT scan of the kidneys without contrast, the local area in which the contour of the kidney bulges outward is always suspicious of a tumor and requires contrast enhancement.

Local bulging of the contour of the left kidney on native CT. Suspicion of hypernephroma. A contrast-enhanced study is required.

Biscuit bud

- an anomaly characterized by complete fusion of both kidneys with the location of the formed biscuit-shaped kidney prevertebral (middle) or near the sacrum - in the pelvic cavity.

Kidney hematoma

- the result of a traumatic impact (most often - a blow with a blunt object in the lumbar region or a fall on the back), in which, as a result of the application of force, blood vessels rupture and blood comes out. Hemorrhages into the renal parenchyma appear on CT as hyperdense areas, the density of which remains approximately the same over a long period of time. Hematomas can be intraparenchymal, subcapsular; may also burrow into the urinary tract.

Hematuria

- a condition in which the hemorrhagic component is detected in the urine. A CT scan of the urinary system can reveal hyperdense blood clots in the bladder or in an enlarged ureter.

Hemorrhagic kidney cyst

- a high-density formation in the kidney (60-70 Hounsfield units), containing fresh or partially lysed blood. All hemorrhagic cysts belong to category 3 according to the Bosniak classification.

An example of a hemorrhagic cyst of the right kidney on computed tomography (marked with an arrow). Hemorrhagic kidney cyst is denser (60...65 Hounsfield units). In this case, the patient has polycytosis of the kidneys with the presence of cysts of various structures and densities.

Hydronephrosis

- a condition manifested by expansion of the renal pyelocaliceal complex on computed tomography as a result of obstruction or obstruction of the ureter due to urolithiasis, with tumors compressing the ureter from the outside.

Left-sided hydronephrosis on computed tomography of the kidneys is manifested by dilation of the renal pyelocalyceal complex. Nephrographic contrast phase.

Hydronephrotic sac

- a condition characterized by extremely pronounced expansion of the calyxes and renal pelvis, in which the medulla and cortex of the kidneys are visualized on computed tomography as a thin strip of tissue. The final stage of hydronephrosis.

Hydrocalyx

- expansion of only one group of calyces, a particular variant of hydronephrosis.

Hydroureter

An example of a sharp unilateral dilatation of the ureter due to obstruction of stones in the area of the mouth is a right-sided hydroureter.

Left-sided hydroureter on axial sections on CT scan of the pelvis (in different patients).

Hypernephroma

— syn. renal cell carcinoma is a malignant kidney tumor of various histological structures (clear cell kidney cancer occurs with a frequency of up to 80%, papillary cell carcinoma with a frequency of 10-15%, chromophobe cell kidney cancer with a frequency of about 5%). Hypernephroma causes deformation of the contour of the kidney; before contrast, it looks like a solid node, isodense to the renal parenchyma, which may also contain calcifications and hemorrhages in the structure. In the arterial phase of contrasting, hypernephromas noticeably intensify due to their high vascularization, after which their heterogeneous structure becomes clearly visible - with the presence of solid and cystic components.

A classic example of hypernephroma on CT scan of the retroperitoneal space is in the form of a space-occupying formation in the upper parts of the left kidney, which has a heterogeneous structure due to different contrasts of the solid and fluid (cystic) components, as well as the presence of hemorrhages.

An example of renal cell carcinoma on CT scan of the kidneys without contrast, in the arterial, venous phases of contrast, as well as in the nephrographic phase.

Changes highly suspicious for hypernephroma on CT scan of the kidneys without contrast.

Hypertrophy of the renal columns

- a variant of kidney development in which thickened Bertini columns can imitate a tumor process.

Functional kidney hypertrophy

- a unilateral increase in the size of the organ that occurs in connection with nephrectomy. The remaining single kidney has a heavy burden of filtering blood, resulting in compensatory hypertrophy.

Glomerulonephritis

- in the acute stage of glomerulonephritis, computed tomography of the kidneys does not reveal any changes, in the chronic stage - atrophy of the renal cortex with an enlargement of the renal sinus can be detected.

Post-resection cortical defect

- a local area in which the cortex is absent, resulting from surgical treatment - marginal resection. With computed tomography of the kidneys, small post-resection defects are difficult to detect due to their filling with retroperitoneal fat.

Kidney dystopia

– location of the kidney in an atypical place, for example, in the pelvis or in the chest cavity (an extremely rare variant of dystopia is the intrathoracic kidney).

An example of pelvic dystopia of the kidney. Computed tomograms visualize a polycystic kidney with multiple large calcified stones, localized in the pelvic cavity presacral - near the sacrum.

Dystopia crossed with fusion

– an anomaly of kidney development, in which there is dystopia of one of the kidneys with its movement on one side of the spine and fusion with the other kidney. CT urography can reveal two ureters, one of which is located in a typical location, and the other crosses the midline and enters the bladder from the opposite side. A renal CT scan can show a single, large kidney on one side of the spine.

Dystopia cross without fusion

- a rare anomaly in which the kidneys do not fuse when one of them is dystopic. With CT, both kidneys are visualized on one side of the spine, however, they lie completely separate from each other and have a separate fat capsule.

Kidney infarction

- death of the renal parenchyma in a limited area (the size of which depends on the degree and level of occlusion of the arterial vessel), manifested on computed tomography of the retroperitoneal organs in the form of a lack of contrast in the area of the renal parenchyma - most often wedge-shaped.

Lack of contrast enhancement of the cortex of the right kidney in the middle and upper sections due to circulatory disorders in this area is an example of a renal infarction.

Calcified kidney stone

- the most commonly detected type of renal calculi, which is characterized by high density (up to 1000 Hounsfield units).

Example of calcified kidney stones on CT scan.

An example of a high-density stone (calcification) in the renal pelvis.

Stone in the lower group of calyxes of the left kidney (calcification).

Xanthine kidney stone

Subcapsular kidney cyst

- renal cyst localized under the capsule.

Cortical kidney cyst

- a cyst localized in the cortical layer of the kidney.

Kidney medullary cyst

-localized in the renal medulla.

Examples of simple cysts of the right kidney, localized mainly in its medulla.

Parapelvic kidney cyst

- localized near the pyelocaliceal complex, can cause compression with impaired urine outflow (rarely).

A huge cyst of the sinus of the right kidney (parapelvical), causing severe compression and deformation of the renal pelvis and calyces, and also leading to disruption of the outflow of urine.

Echinococcal kidney cyst

- cystic kidney damage caused by echinococcus. On CT, renal echinococcosis manifests itself as the presence of cysts with clearly defined contours, with often detected calcifications and septa. The walls of echinococcal cysts and septa are enhanced after the administration of contrast.

Classification of kidney cysts according to Bosniak

- assumes a conditional division of all renal cysts into 4 classes depending on the degree of their oncological alertness - from 1st (uncomplicated simple cysts) to 4th (definite malignant neoplasm).

The images show an example of a simple cyst of the lower pole of the right kidney, which does not contain a soft tissue component, septa, hemorrhages or calcifications in its structure. This cyst belongs to category 1 according to Bosniak.

Pelvicalyceal complex

- a structure consisting of the renal calyces and the renal pelvis.

Kidney contusion

- traumatic injury to the kidney, in which the leading sign on CT is edema, manifested in the form of an increase in the size of the kidney, blurred contours, and narrowing of the pyelocaliceal complex.

Corticomedullary phase

- one of the phases of contrast in computed tomography of the kidneys, obtained by scanning 20-30 seconds after the administration of contrast, performed for the purpose of visualizing the renal vessels, as well as well-vascularized kidney tumors.

CT urography

— display of the pyelocaliceal complex of the kidney and ureters obtained with CT scan of the kidneys after the injection of contrast into the vein.

Kidney lymphoma

- most often a secondary kidney disease that occurs with non-Hodgkin's lymphoma, as well as with post-transplant lymphoma. Renal lymphoma on CT may look like: a solitary node, deforming the contours of the kidney and infiltrating perirenal fat; multiple nodes of both kidneys up to 5 cm in size, which are clearly visible after contrast enhancement; diffuse changes in the kidney in the form of a decrease in the degree of enhancement of the renal parenchyma in the nephrographic phase and a decrease in renal excretion; retroperitoneal node - with fouling of the renal sinus and ureter.

Damage to the lymph nodes at the hilum of the kidney in lymphoma.

Kidney lipoma

- a tumor containing only adipose tissue (density -80...-120 Hounsfield units).

An example of a small lipoma of the left kidney is a peripherally located hypodense area of a round shape, having a fat density (in this example -100 Hounsfield units).

Mesenchymal kidney tumors

- a collective term that includes tumors such as lipomas, fibromas, leiomyomas, histiocytomas - rare tumors that do not have specific signs on CT scans of the kidneys.

Kidney metastases

- secondary kidney damage due to tumors of a different location. For example, bronchogenic cancer can metastasize to the kidneys. On CT, renal metastases may appear as multiple hypodense in the nephrographic phase of formation. The presence of metastases in other organs - adrenal glands, liver - is also characteristic.

Native CT scan of the kidneys

- computed tomography of the kidneys, performed without the introduction of a contrast agent. Used for the diagnosis of urolithiasis, obstructive lesions of the maxillary tract and ureters, and to identify high-density stones.

Chronic interstitial nephritis

- a disease of the renal interstitium caused by taking analgesics for a long time. A computed tomography scan of the kidneys reveals changes in the form of a decrease in the size of the kidneys and the formation of calcifications of the renal papillae.

Atrophic changes in both kidneys due to interstitial disease.

Nephroblastoma

— syn. Wilms tumor is a tumor of the renal parenchyma, most often found in childhood (up to 5 years). On CT, nephroblastoma is visualized as a hypodense formation, deforming the contour of the kidney, having heterogeneous density due to hemorrhages and necrotic foci, less often - fat and calcifications. Metastasizes to the lymph nodes at the hilum of the kidney, to the para-aortic lymph nodes.

Nephrographic phase

- one of the phases of contrast enhancement in CT scans of the kidneys, in which the renal cortex and medulla have the same density. This phase occurs 80-120 seconds after the administration of contrast, in which the probability of detecting tumors, especially small ones, is highest.

Nephrocalcinosis

- total calcification of the medulla and cortex of the kidneys, which on computed tomography become sharply hyperdense and extremely dense.

Nephroptosis

- low location of the kidney, low origin of the renal artery on the corresponding side, an atypically long and tortuous ureter.

The reformation in the coronal plane demonstrated moderate right-sided nephroptosis. Pay attention to the level at which the right and left kidneys are located - the right one is at least 2/3 of the height of the lumbar vertebra below.

Nephrectomy

- surgical removal of the kidney. A CT scan reveals scar tissue in the renal bed if the operation was performed long ago, and fresh blood and swelling in recent cases.

Case demonstrating right nephrectomy. The CT image shows a single left kidney, and a metal clip on the right vascular bundle of the kidney.

Inferior vena cava tumor thrombosis

– a condition that can occur when a kidney tumor (right) grows into the inferior vena cava. It indicates the advanced stage of the tumor process and is a marker of stage T4 according to the TNM classification.

Tumor of the upper pole of the right kidney grows into the inferior vena cava, in which multiple gas bubbles are also visualized. The prognosis in this case is extremely unfavorable.

Obstruction of the ureteropelvic junction

- a congenital anomaly of the kidneys, manifested by narrowing in the area of the transition of the pelvis to the ureter, which does not lead to the development of hydronephrosis.

Oncocytoma

- benign tumor of the kidney from the epithelium of the renal tubules. On computed tomography of the kidneys, it looks like a single formation with expansive growth, equal in density to the hepatic parenchyma in native studies and intensifying after the introduction of contrast in the form of a “wheel with spokes” due to the presence of a central scar of a characteristic (star-shaped) shape.

Perl-Mann tumor

— syn. renal cystadenoma, multilocular cystic nephroma.

Kidney papilloma

- a common tumor characterized by damage to any part of the urinary tract - renal pelvis, ureter, bladder. It is a precancerous condition.

Anterior pararenal space

- an anatomical region containing fatty tissue, directly adjacent to the anterior fascia of Gerota on one side, and to the capsule of the spleen and pancreas on the other side.

Pararenal space posterior

- an anatomical area in which fatty tissue is located, limited by the posterior fascia of Gerota on one side, and the lumbar muscles on the other.

Perirenal space

- an area delimited by the anterior and posterior fascia of Gerota, containing perirenal fat (the fatty “capsule” of the kidney).

Persistent embryonic lobulation of the kidney

- a development option in which defects in the contour of the renal parenchyma are detected towards the renal columns.

Pyelonephritis

- inflammation of the renal interstitium with involvement of the pelvis in the process, caused by an infectious agent. With pyelonephritis, CT can detect an enlarged kidney, blurred contours due to edema of the renal parenchyma and perirenal tissue, as well as local thickening of Gerota's fascia - if the inflammatory process spreads to them.

Changes in the kidney on CT scan with pyelonephritis.

Emphysematous pyelonephritis

- a severe variant of the inflammatory process in the kidney, caused by the development of gas-forming flora, which on computed tomography of the kidneys manifests itself as the presence of gas bubbles in the perinephric tissue, under the kidney capsule, in the pelvis, as well as signs of edema.

Pyelonephritis xanthogranulomatous

- a chronic inflammatory process in the renal cortex and in the medulla, which occurs secondary to obstruction of the urinary tract due to urolithiasis. Occurs mainly in women. With xanthogranulomatous pyelonephritis, stones in the renal pelvis are often detected, sometimes coral-shaped ones, as well as signs of hydronephrosis, with the expansion of the calyces and the presence of detritus and xanthoma bodies in their cavities.

Pyonephrosis

- a condition that develops when the kidney is infected against the background of existing hydronephrosis. A CT scan of the retroperitoneum during pyonephrosis reveals a significant expansion of the renal collecting system with the presence of infected fluid with a density of 20...30 Hounsfield units.

Caseous pyonephrosis

- the final stage of development of kidney tuberculosis, in which caseous purulent melting occurs, followed by wrinkling and diffuse calcification.

Pyocalyx

- infection of one group of calyces with existing hydronephrosis or hydrocalyx - a local variant of pyonephrosis.

Squamous cell kidney cancer

- malignant kidney formation with a tendency to invasive growth. The tumor is localized in the renal pelvis and has the appearance of a node with a lobular structure. May cause hydronephrosis due to obstruction of the urinary tract. In the bladder with squamous cell kidney cancer, hyperdense blood clots can be seen.

Horseshoe kidney

- fusion of the kidneys in the region of the lower pole due to the presence of an isthmus consisting of connective or renal tissue. The kidney has the characteristic appearance of a horseshoe.

An example of visualization of a horseshoe kidney on contrast-enhanced computed tomography in the arterial and excretory phases. In the right image, arrows indicate the renal arteries (there are two of them, one on each side of the horseshoe kidney), in the image on the left and in the middle, arrows indicate separate ureters.

Renal vein thrombosis

- obstruction of the patency of the renal vein as a result of its occlusion by a thrombus. On CT scan, the renal vein is sharply dilated, full of blood (sometimes more than 2 cm), the degree of contrast enhancement of the vein is lower compared to the other side. In some cases, it is possible to directly visualize a thrombus in the lumen of the vein. If the thrombus intensifies in the arterial phase, a tumor of the renal vein can be suspected.

Kidney Page

- compression of the kidneys by large hematomas located subcapsularly, and the development of secondary renal hypertension.

Simple renal cyst

- hypodense formation with a density of 10...15 Hounsfield units in the kidney, not containing a solid component, calcifications, septa, blood. A common finding on CT scans of the kidneys. Simple cysts are not enhanced by contrast.

Pseudotumor of the kidney

- a volumetric process of the kidney, simulating tumor growth, but being a reflection of normal anatomical renal structures, for example, an enlarged column of Bertinius - an outgrowth of the renal cortex.

Renal rupture

- damage to the cortical and (or) medulla of the kidney, expressed to varying degrees depending on the applied traumatic force and the conditions of the injury.

Renal rupture, AAST classification

- 1 tbsp. - contusion or hematoma of the kidney; 2 tbsp. - renal cortex rupture less than 1 cm without urine extravasation; 3 tbsp. - a rupture of the renal cortex of more than 1 cm without damage to the collecting system and without extravasation of urine; 4 tbsp. - rupture of the renal parenchyma (cortical and medulla of the kidney, as well as the collecting system); 5 tbsp. - rupture of the parenchyma as in the case of stage 4, but with separation of the vascular bundle of the kidney and its devascularization.

Ureteral cancer

- looks on a CT scan of the ureters as a formation of soft tissue density, causing obstruction of the lumen and the development of hydroureter, and then hydronephrosis, or as thickening of the ureteral wall. In this condition, the distal part of the ureter is distended, filled with urine with a density of 12...20 Hounsfield units.

Renal cortical necrosis

- a condition in which death of the renal cortex occurs in a limited area or diffusely against the background of sepsis, septic shock. A CT scan of the kidneys with contrast in case of renal necrosis can reveal the absence of contrast in the renal cortex, and subsequently - after a week or more - calcification of the cortical layer begins and the progression of atrophic changes in the kidneys.

Soft tissue ring sign

— display of a thickened wall of the ureter when it is obstructed by a high-density calculus. On computed tomography, the ureter on axial sections appears as a ring structure with a hypodense wall (ring) and a hyperdense center (urinary stone).

An observation illustrating the symptom of a “soft tissue ring” during ureteral obstruction with a calcified stone – a high-density center and a low-density soft tissue “rim” along the periphery.

Stage T of renal cell carcinoma

(according to the TNM classification) - determined based on the size of the tumor node and its invasion of surrounding tissues. T1 - node less than 7 cm in largest size, localized in the renal parenchyma; T2 - a node larger than 7 cm in largest size, localized in the kidney; T3 - invasion of perinephric tissue, as well as adjacent vessels, is observed; T4 - tumor invasion of the anterior or posterior fascia of Gerota is observed.

An example of renal cell carcinoma in different phases of contrast enhancement: native, arterial and acute. The tumor node corresponds to T1 stage according to TNM, since it is less than 7 cm in diameter and does not grow into surrounding tissues.

Stage N renal cell carcinoma

(according to TNM classification) - displays damage to the lymph nodes. N1 - there is a single enlarged lymph node less than 2 cm in largest size; N2 - there is a single lymph node more than 2 cm in largest size, or multiple lymph nodes less than 5 cm in size; N3 - there are lymph nodes larger than 5 cm.

Ureteral stricture

- a condition manifested by narrowing of the lumen of the ureter due to injury, inflammation, ionizing radiation (radiation therapy). Ureteral strictures are the cause of hydronephrosis.

Kidney tuberculosis

- one of the most common forms of extrapulmonary localization of tuberculosis infection. With computed tomography, renal tuberculosis usually does not give specific symptoms and manifests itself in the form of a productive form (with the presence of multiple tubercles in the cortical layer, hypodense in relation to the parenchyma), or an ulcerative-cavernous form (in the form of destructive changes in the kidneys with the development of multiple abscesses, the appearance calcifications, atrophic changes in the kidney parenchyma).

Perirenal fat severity

- a sign of urinary tract obstruction caused by urolithiasis.

Kidney duplication

- a developmental anomaly consisting in the presence of two separate fully formed kidneys on one side, supplied with blood by separate renal arteries, the outflow of venous blood from which is carried out through separate renal veins.

Duplication of the renal pelvis

- a development option in which there are two separate pelvises (and often two ureters) in one kidney.

Duplication of the ureter

- a development variant manifested by the presence of two separate ureters (in this case, duplication of the renal pelvis can also be detected). Duplication of the ureter can also be detected only in the upper sections - the so-called. ureter fissus.

Urolithiasis

- a term denoting the presence of urinary stones in the pyelocaliceal complex of the kidney and (or) in the ureter.

Urothelial cancer

- a malignant tumor of the renal pelvis, often also affecting the ureter and bladder.

Gerota's fascia anterior

— syn. anterior renal fascia is a connective tissue septum that separates the retroperitoneal tissue, in which the kidneys are located, from the fatty tissue of the abdominal cavity.

Gerota's fascia posterior

— syn. Zuckerkandl's fascia is a connective tissue septum delimiting the fatty capsule of the kidney at the back.

Fibrolipomatosis of the pelvis

- formation of the renal pelvis with a density corresponding to the density of fat and higher - depending on the ratio of connective tissue and fat components. Fibrolipomatosis is characterized by low-intensity sharp contrast enhancement.

Kidney cystadenoma

- a benign tumor consisting of a large number of cysts filled with myxomatous contents. CT scan of the kidneys is visualized as a large tumor (at least 3 cm, consisting of many cysts, sharply demarcated from the surrounding tissues. In approximately half of the cases with cystadenoma, calcifications are detected; hemorrhages and necrosis are much less common.

Excretory phase

- one of the phases of contrast enhancement (late) in CT scans of the kidneys, in which the pyelocaliceal complex, ureters and bladder are contrasted. Performed more than five minutes after the start of contrast administration.

Excretory phase delayed

- performed 15 or more minutes after the start of contrast injection into the vein, it is used to detect urineomas, and also allows you to evaluate the retention time of contrast in the kidney tubules.

Extravasation of urine

- a condition that occurs as a result of a violation of the integrity of the wall in any part of the urinary tract and the release of urine into the surrounding tissue.

Urography

– display of the organs of the urinary system obtained from their contrast X-ray or tomographic examination.

Urography excretory

– X-ray examination of the organs of the urinary system (CT or classical radiography), the purpose of which is to visualize the organs of the urinary system after the introduction of water-soluble contrast into a vein.

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What does hyperechogenicity of pyramids mean?

The pyramids of the kidneys are certain areas through which urine enters the collecting system after filtering fluid from the bloodstream.

Important! Echogenicity is the ability of wave reflection of sound from a solid or liquid substance. All organs are echogenic, which makes it possible to do ultrasound. Hyperechogenicity is a reflection of increased strength, revealing inclusions in organs. Based on the monitor readings, the specialist identifies the presence of an acoustic shadow, which is a determining factor in the inclusion density. Thus, if the kidneys and pyramids are healthy, the study will not show any wave abnormalities

Symptoms of hyperechogenicity

Syndrome of hyperechoic renal pyramids causes pain in the lower back of a cutting, stabbing nature

Hyperechoic renal pyramid syndrome has a number of symptoms:

Body temperature changes;
Pain in the lower back of a cutting, stabbing nature;
Changes in the color and smell of urine, sometimes blood droplets are observed;
Abnormal stool;
Nausea, vomiting.

Types of hyperechoic inclusions

All formations are divided into three types, based on what picture is visible on ultrasound

All formations are divided into three types, based on what picture is visible on ultrasound:

A large inclusion with an acoustic shadow most often indicates the presence of stones, focal inflammation, and disorders of the lymphatic system;

A large formation without a shadow can be caused by cysts, fatty layers in the sinuses of the kidneys, tumors of various types or small stones;

Small inclusions without a shadow are microcalcicates, psammoma bodies.

Possible diseases depending on the size of inclusions:

Urolithiasis or inflammation - manifests itself as large echogenic inclusions.

Single inclusions without a shadow indicate:

hematomas;
sclerotic changes in blood vessels;
sand and small stones;
scarring of organ tissue, for example, parenchymal tissue, where scarring occurred due to untreated diseases;
fatty seals in the sinuses of the kidneys;
cystosis, tumors, neoplasms.

Important! If the device monitor shows obvious sparkles without shadows, then in the kidneys there may be an accumulation of compounds (psammoma) of a protein-fatty nature, framed by calcium salts or calcifications. It is not recommended to ignore this symptom, as this may be the beginning of the development of malignant tumors. In particular, oncological formations include calcifications in 30% and psammonic bodies in 50%.

Source

03-med.info

Structure and purpose of parenchyma

In addition to its most well-known purpose - to be part of the excretory (excretory) system, the kidney also performs the functions of an organ:

endocrine (intrasecretory);
osmo- and ion-regulating;
participating in the body both in general metabolism (metabolism) and in hematopoiesis - in particular.

Cortical and medulla layers

According to the generally accepted position, the two layers of the kidney are called:

cortical;
cerebral.

Glomeruli and urine formation

The first is a capillary glomerulus, completely immersed in a cup-shaped depression in the center of the flask-shaped expanded primary element of the nephron - the Shumlyansky-Bowman capsule.

They arise as a result of the entry of the “legs” of some podocytes into the spaces between the same processes of other, neighboring cells, forming a structure reminiscent of a zipper lock.

Parenchyma thickness at different ages

Atrophic processes in the kidneys are associated both with maintaining a certain lifestyle and with the progression of diseases acquired during life.

voluntary chronic intoxication;
sedentary lifestyle;
the nature of the activity associated with stress and occupational hazards;
living in a certain climate.

Column Bertini

Parenchymal bridge

A kidney is an organ that can take any shape: from the classic bean-shaped to a horseshoe-shaped or even more unusual.

Regeneration ability

Diffuse changes and echogenicity

These are all diseases and conditions that lead to sclerosis of blood vessels.

The list can begin with infectious processes in the body (flu, streptococcal infection) and chronic (habitual household) intoxications: drinking alcohol, smoking.

The concept of echogenicity implies the heterogeneity of the structure of an organ with varying degrees of permeability of its individual zones for ultrasound examination (ultrasound).

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Hyperechoic renal pyramid syndrome

Characteristic symptoms that cause kidney problems

Symptoms Associated with Kidney Disease

Types of hyperechoic inclusions and diagnosis

Website about kidney diseases

Therapeutic measures and prevention

Necessary treatment

Clinical manifestations

Partial or complete rupture of the collecting system image at the same location indicates a duplex kidney with separate ureters and blood supply for each half.

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Concepts - hyperechogenicity and acoustic shadow?

On ultrasound, hyperechoic inclusions appear as white spots.

Kidneys and paranephria are normal

The kidneys are located on both sides of the spinal column. Their upper third is covered by ribs that pass anteriorly above them, descending downward. When viewed from behind and from the side, the longitudinal axes of the kidneys form an acute angle with the spine. The transverse axes of the kidneys form an angle of approximately 45° with the sagittal plane. The kidneys are located retroperitoneally. The right kidney is at the level of Th-12-L-4, the left kidney is located higher - at the level of Th-11-L3 vertebra. However, determining the position of the kidney relative to the vertebrae is quite inconvenient, therefore, in echographic practice, the hypoechoic acoustic “shadow” from the twelfth rib, the dome of the diaphragm (or the diaphragmatic contour of the liver), the hilum of the spleen, and the contralateral kidney are used as a guide to determine the position of the kidney. Normally, the acoustic “shadow” "from the twelfth rib crosses (during longitudinal scanning from the back parallel to the long axis of the kidney) the right kidney at the level of the boundaries of the upper and middle third, the left kidney at the level of the renal hilum. Usually the kidneys are clearly visible with the patient lying on his side. A longitudinal section of the kidney is visible when the sensor is placed on the side of the intercostal line, during deep inspiration the kidneys move down from under the acoustic shadow of the ribs and are visible in their longitudinal section.

Rice. 1 Visualization of the right kidney. The sensor is located in the posterior axillary line on the right. N - kidney, L - liver.

The upper pole of the right kidney is located at the level or slightly below the superior diaphragmatic contour of the right lobe of the liver. The upper pole of the left kidney is located at the level of the hilum of the spleen. The distances from the upper pole of the right kidney to the contour of the diaphragm and from the upper pole of the left kidney to the hilum of the spleen depend on the degree of development of the perinephric tissue of the subject.

To obtain a longitudinal sonogram of the right kidney with the patient in the supine position, use the serody shown in Fig. 2.

Rice. 2. To obtain an image in the lateral plane, the transducer is moved laterally from the paramedial position. This plane is used to assess the pleural angle distal to the diaphragm (D) and to obtain a longitudinal view of the kidney (K) posterior to the liver (L).

As with a complete examination of any other organ, it is necessary to examine the kidney in a second projection to study its cross section. The sensor can be installed directly under the costal arch or in the area of the last intercostal space. It should be remembered that the lower parts of the kidney are located closer to the sensor, the upper parts are further away from it, i.e. the longitudinal axis goes from top to bottom and from the central axis of the body in the lateral direction.

Rice. 3.a-c Visualization of the right kidney in a lateral cross-section

Cross-sectional sonography of the right kidney can be performed with the patient in the supine position.

Rice. 4. When assessing a longitudinal section of the kidney, the sensor is rotated to a transverse position in the mid-abdomen and moved to the midline. The kidney will be visualized in transverse section, posterior to the liver (L). At the level of the renal hilum, the vascular pedicle of the kidney will be visualized in the anteroposterior direction, including the renal vein (Vr) and renal artery (Ar); the ureter can also be identified. In patients with poorly defined subcutaneous fat, the entry of the renal vein into the vena cava (Vc), the origin of the renal artery from the aorta (Ao), and the gallbladder (Gb) near the inferior border of the liver can be visualized in one image.

Visualization of the body of the left kidney is carried out similarly to the visualization of the right kidney.

The left kidney is also located in a kind of triangle, the sides of which are the spine, muscles and spleen. The spleen covers almost half of the kidney. The lower half of the kidney is bordered laterally by the descending colon and the left flexure of the colon. The colon goes around the kidney in front. Its upper pole is covered in front by the stomach. Thus, access to the left kidney is optimal from the back and side through the intercostal space using the spleen as an ultrasound window. Nevertheless, the quality of visualization of the left kidney is almost always much worse than the right, especially if this is also accompanied by the addition of intestinal gases.

Fig.5 Visualization of the left kidney. N - kidney, Mi - spleen, Mr - psoas muscle.

Normal kidney sizes:

Kidney length: 10-12 cm Kidney width: 4-6 cm Respiratory mobility: 3-7 cm Parenchyma thickness: 1.3-2.5 cm

The cut shape of a normal kidney in all projections is bean-shaped or oval. The contour of the kidney is usually smooth, and if there is preserved fetal lobulation of the kidney, it is wavy (this is a variant of the normal structure of the kidney). The sonographic characteristics of the renal capsule and parenchyma of the normal kidney are generally accepted. Along the periphery of the ultrasound section of the kidney, a fibrous capsule is determined in the form of a hyperechoic, smooth, continuous structure 2-3 mm thick. Next, the parenchyma layer is determined.

Normal kidney parenchyma has slightly reduced or equal echogenicity compared to splenic or liver parenchyma. The thickness of the parenchyma should be at least 1.3 cm. The ratio of the thickness of the parenchyma to the width of the renal sinus (= PS index) decreases with age:

PS index (depending on age):

< 30 лет: 1,6: 1

< 60 лет: 1,2-1,6: 1

>60 years: 1.1:1

The renal hilum is determined echographically in the form of a “break” in the medial contour of the renal parenchyma, while when scanning from the anterior abdominal wall, at the top of the scan, an anteriorly located anechoic tubular structure is visualized - the renal vein, below - a hypoechoic renal artery located posteriorly. The renal hilum together with the renal vein is usually clearly visible in cross section. Due to their small size, the ureter and renal artery are often difficult to identify.

The parenchyma is heterogeneous and consists of two layers: the cortex and the medullary substance (or the substance of the kidney pyramids). The morphological substrate of the renal cortex (kidney cortex) is predominantly the glomerular apparatus, convoluted tubules, interstitial tissue containing blood and lymphatic vessels, and nerves. The renal cortex is located along the periphery of the ultrasound section of the kidney with a thickness of 5-7 mm, and also forms invaginations in the form of columns (columnae Bertini) between the pyramids. The echogenicity of the renal cortex is usually slightly lower or comparable to the echogenicity of the normal liver parenchyma.

The medullary substance contains loops of Henle, collecting ducts, ducts of Bellini, and interstitial tissue. On a standard longitudinal section, the hypoechoic medullary pyramids appear like strands of pearls between the parenchymal cortex and the centrally located echogenic collecting system. They should not be mistaken for tumors or cysts. Often this difference in echogenicity is the cause of a false-positive diagnosis of hydrocalycosis, when very dark, low-echogenicity pyramids are mistaken by novice ultrasound doctors for dipated cups. Modern histomorphological studies of the kidney parenchyma and their comparison with the echographic picture suggest that the pronounced echographic corticomedullary differentiation is due to a significant difference in the number of fat vacuoles in the epithelium of the tubular structures of the cortex and pyramids. However, the different echogenicity of the cortex and pyramids cannot be explained only by the different content of fat vacuoles in the epithelium of the tubular structures, because It is known that the echogenicity of the pyramids of the kidney at a high level of diuresis is significantly lower than the echogenicity of the pyramids of the same kidney under normal conditions, while the number of fat vacuoles does not change depending on the level of diuresis. It is also impossible to explain the low echogenicity of the pyramids by the presence of fluid in the tubular structures, because The resolution of the ultrasound device under any conditions does not allow differentiating the lumen of the tubule and the liquid in it. It can be assumed that the low echogenicity of the medullary substance is associated with: 1) a high content of glycosaminoglycans in the interstitial tissue, where most of the functional processes that ensure ion exchange, reabsorption of water and electrolytes, and urine transport occur; glycosaminoglycans are able to “bind” liquid, according to the authors of the hypothesis, “very quickly swelling and swelling; 2) the presence of smooth muscle fibers in the interstitial tissue surrounding the excretory ducts of the renal papilla.

Often, Bertin's column extends quite far beyond the internal contour of the parenchyma into the central part of the kidney - into the renal sinus, dividing the kidney more or less completely into two parts. The resulting peculiar parenchymal “bridge”, the so-called. the hypertrophied column of Bertin is the non-resorbed parenchyma of the pole of one of the kidney lobules, which during ontogenesis merge to form the adult kidney. The kidney pyramids are defined as triangular-shaped structures with reduced echogenicity compared to the cortex. In this case, the top of the pyramid (pyramidal papilla) faces the renal sinus - the central part of the kidney slice, and the base of the pyramid is adjacent to the parenchyma cortex, located along the periphery of the slice. The renal pyramids have a thickness of 8-12 mm (the thickness of the pyramids is defined as the height of the triangular structure, the apex of which faces the renal sinus), although the normal size of the pyramids largely depends on the level of diuresis. Normally, the echographic differentiation of the cortex and pyramids is pronounced: the echogenicity of the cortical substance is significantly higher than the echogenicity of the pyramids of the kidney.

Standard options

The normal shape of the kidney may have some features reflecting its embryonic development. Hyperplastic columns of Bertini can protrude from the parenchyma into the pelvis and do not differ in echogenicity from the rest of the renal parenchyma.

Isoechogenic parenchymal bridges can completely separate the collecting system. Partial or complete rupture of the collecting system image at the same location indicates a duplex kidney with separate ureters and blood supply for each half. Indeed, difficulties usually arise when diagnosing duplication of the pyelocaliceal system, which is a very common cause of false (false-positive and false-negative) conclusions. Sometimes the presence of a parenchymal “bridge” - the so-called hypertrophied column of Bertin, separating the renal sinus, is the reason for making an echographic diagnosis of incomplete duplication of the pyelocaliceal system. Indeed, cases with complete division of the renal sinus by a parenchymal bridge in more than 50% of cases are accompanied by doubling pelvis and calyces, however, the most common incomplete ("shallow") bridges are not an ultrasound sign of duplication of the pyelocaliceal system, although they can produce a displacement of the group of cups detected during excretory urography. The displacement of the group of cups is perceived by the radiologist as a sign of a volumetric process in the kidney. In this case, ultrasound examination will help to exclude the presence of a space-occupying process in the renal sinus.

Fig.8. Echogram of the kidney with a double pyelocaliceal system. The kidney is normally formed. Only a significant increase in the length of the kidney (up to 15.6 cm) made it possible to suspect the presence of doubling of the pyelocaliceal system according to echography.

Prevertebral parenchymal bridging of a horseshoe kidney may be mistaken for pre-aortic lymphadenopathy or thrombosis of an aortic aneurysm. Among abnormally fused kidneys, the horseshoe kidney is the most common. Most often (in approximately 90% of cases), fusion is observed with the lower poles, much less often - with the middle and upper segments.

Rice. 9. Horseshoe kidney (v). A space-occupying formation located in front of the aorta, which has an oval shape in a longitudinal section.

Kidney dystopia is an anomaly of kidney development in which the kidney does not rise to its normal level during embryogenesis. There is a homolateral dystopia of the kidney, with the kidney located on “its” side. Among homolateral dystopias, lumbar, iliac and pelvic dystopia are distinguished. Heterolateral dystopia is characterized by lower detection of the kidney, but not on its own side, but on the opposite side. In this case, variants of heterolateral dystopia with and without fusion of the kidneys are possible.

Nephroptosis, or pathological displacement of the kidney, occurs with congenital or acquired weakness of the ligamentous-supporting apparatus of the kidney, while the main role in the normal fixation of the kidney in the renal bed is assigned to the perinephric tissue.

When echographic detection of an abnormally located kidney, difficulties usually arise in the differential diagnosis of nephroptosis and dystopia. It must be remembered that a kidney with nephroptosis has a normal length ureter and a vascular pedicle located at the usual level (level L1-L2 of the lumbar vertebrae). A dystopic kidney has a short ureter and vessels extending from large trunks at the level of the kidney.

The lobulated contour of the kidney can be visible in children and young people as a manifestation of fetal lobulation, characterized by a smooth surface of the kidney with the presence of notches between the individual medullary pyramids. These changes must be distinguished from renal infarcts, which may be found in elderly patients with atherosclerotic renal artery stenosis.

Limited parenchymal thickening along the lateral margin of the left kidney (or at the margin of the renal sinus), usually just below the lower pole of the spleen, is found in up to 10% of patients. This anatomical variant, often called a “camel hump” kidney, can sometimes be very difficult to distinguish from a true kidney tumor. These conditions are described as pseudotumors and are also variants of the normal kidney structure. One of the distinguishing features of pseudo-tumors is “bulging” of the parenchyma when preserved fetal lobulation of the kidney, in contrast to the tumor, is the preservation of the parallelism of the outer and internal contours of the parenchyma, the preservation of the normal echostructure of the parenchyma.

Atrophic and inflammatory changes in the kidneys

The kidneys respond to various inflammatory processes with heterogeneous sonographic changes. In acute pyelonephritis or glomerulonephritis, the picture may be normal in the early stages.

Later, an enlargement of the kidney is noted, with a predominant increase in the anterior-posterior size of the kidney, as a result of which the echographic section of the kidney becomes round, and not oval or bean-shaped, as is normal. There is thickening of the parenchyma and a diffuse decrease in the echogenicity of the parenchyma. Edema causes an increase in size, and interstitial infiltration causes an increase in the echogenicity of the parenchyma with increased clarity of its boundaries relative to the hypoechoic pyramids. This pattern is called “knocked out medullary pyramids.” Compared with adjacent liver or spleen parenchyma, renal parenchyma in such situations appears more echogenic than normal renal parenchyma.

Fig. 10. Acute pyelonephritis: enlarged hypoechoic kidney with obliterated sinus and fluid level in the renal pelvis.

This type of echographic changes is usually accompanied by acute renal failure. At the same time, the appearance of the syndrome of “discharged pyramids” is based on ischemia of the renal cortex with shunting of blood through the venules of the medulla. Ischemia of the renal cortex develops as a result of interstitial edema, cellular infiltration of the interstitium and peripheral vasoconstriction. The echogenicity and cross-sectional area of the renal sinus also decrease as a result of fiber resorption renal sinus, compression of the renal sinus by thickened parenchyma.

Fig. 11. Kidney enlargement in acute glomerulonephritis.

Interstitial nephritis can be caused by chronic glomerulonephritis, diabetic or urate nephropathy (hyperuricemia as a manifestation of gout or increased metabolism of nucleic acids), amyloidosis or autoimmune diseases, but it is impossible to establish the true cause by increasing the echogenicity of the parenchyma. Another sign of inflammation is an unclear boundary between the parenchyma and the collecting system.

Rice. 12. a, b Thrombosis of the renal vein, a Acute thrombosis of the renal vein in septic pyelonephritis: enlarged kidney (K, cursors) with a vague hypoechoic structure and spotty-striped hypoechoic transformation of the central echo complex. C - atypical cyst, b Spectral analysis shows an extremely high IR of 0.96.

Para- and perinephritis are often visualized as zones with unclear, uneven contours of reduced echogenicity. With abscess formation, with purulent melting of paranephrium, anechoic cavities are visualized around the kidney, in which suspension can be detected. A sharp decrease in the respiratory mobility of the kidney is determined. In the presence of viscous purulent contents in the case of “old”, chronic paranephritis, tumor-like masses of mixed echogenicity can be visualized around the kidney. In this case, the boundaries of the kidneys will be unclear, however, the purulent-necrotic masses themselves are extremely poorly differentiated in the retroperitoneal space from fatty tissue. The figure shows an echographic picture purulent apostematous pyelonephritis. An enlarged, deformed kidney is visible, with sharply thickened, heterogeneous parenchyma, with distinct foci of destruction. The purulent process has spread to the paranephrium with the development of purulent paranephritis (the hypoechoic zone around the kidney is marked by an arrow).

Rice. 13. Echogram of the kidney (1) with acute purulent paranephritis, which developed against the background of apostematous pyelonephritis. Paranephritis (2) is defined as a crescent-shaped zone of reduced echogenicity around the kidney.

Renal artery stenosis causes peripheral infarctions and can also lead to a general decrease in kidney size, which, however, may be a manifestation of recurrent or chronic inflammation.

Rice. 14. Shriveled kidney. Significant reduction of the kidney. Fuzzy boundary between the cortical and medulla layers.

Severe parenchymal thinning, found in the end stage of chronic nephritis, leads to renal atrophy, which is often associated with degenerative calcification or stones with associated acoustic shadowing.

Fig. 15. Reduction in kidney size with pyelonephritis (83.9 mm, cursors): areas of thinning of the parenchyma due to scarring, leading to the appearance of a wavy contour of the surface. C - flat cyst. Fine needle aspiration of a suspected abscess of the adrenal epithelium.

An atrophied kidney may be so small that it cannot be detected sonographically. The associated decrease in excretory function can cause compensatory hypertrophy of the opposite kidney. With a unilateral small kidney, its PS index should be determined. If the PS index is normal, we can talk about congenital renal hypoplasia.

Although sonography does not provide a differential diagnosis of inflammatory kidney disease, it is valuable in monitoring any renal inflammation during treatment, to rule out complications (eg, acute obstruction) and to guide percutaneous biopsy.

Kidney cysts

Renal cysts are anechoic formations and give distal enhancement. Additional diagnostic criteria for kidney cysts are the same as for liver cysts. Cysts are divided into peripheral cysts along the surface of the kidney,

Rice. 16. Peripheral cyst of the upper pole of the kidney.

Parenchymal cysts and cysts of the renal sinus, which in the future must be differentiated from the renal pelvis dilated due to obstruction.

Fig. 17. Large parenchymal cyst.

A description of the cyst should include its size, as well as its approximate location (upper, middle, or lower third of the kidney). The discovery of multiple renal cysts is not of significant clinical significance, although regular follow-up examinations are recommended.

Fig. 18. Renal sinus cyst.

In contrast, in polycystic kidney disease in adults there are an incalculable number of cysts that constantly increase in size. When the cysts reach a significant size, the patient may complain of pain and a feeling of heaviness in the upper abdomen.

Fig. 19. Polycystic kidney disease.

Subsequently, polycystic disease causes kidney atrophy due to displacement and thinning of the organ parenchyma, which leads to the development of renal failure at a young age and requires dialysis or a kidney transplant.

Signs of obstruction and urinary tract. Differential diagnosis of urodynamic disorders

With obstruction of the urinary tract, the normal passage of urine through the urinary tract is disrupted; the fluid more or less completely fills the cavities of the collecting system of the kidneys, as a result of which visualization of the collecting system becomes possible.

The renal collecting system appears as a highly echogenic central complex that is intersected only by small, thin vascular structures. With increased diuresis after fluid intake, the renal pelvis can stretch and take on the appearance of an anechoic structure. Similar manifestations can be caused by various variants of the development of the extrarenal pelvis. In both cases, dilatation does not affect the major and minor calyces. There are a number of pathological conditions in which the collecting system is also visualized, but the cause of this is not obstruction. These are acute and chronic renal failure in the stage of polyuria, chronic pyelonephritis, accompanied by sclerosis and deformation of the calyx and pelvic structures, renal tuberculosis with deformation, amputation, sclerosis of the calyces, formation of cavities, diabetic nephropathy with a secondary pyelonephritic process and polyuria, papillary necrosis, followed by involvement of the calyces in the sclerotic process. Vesicopelvic reflux causes visualization of the collecting system during filling of the bladder (passive reflux), with active contraction of the detrusor (active reflux) with possible subsequent hydronephrotic transformation of the kidney. If the ultrasound diagnostician is tasked with identifying reflux, it is advisable to examine the patient under normal water load conditions, because the presence of fluid in the pelvis with increased diuresis can lead to a false positive diagnosis of reflux. Ultrasound diagnosis of passive reflux is difficult, since dilatation of the pelvis occurs in almost all healthy people when the bladder is overstretched. A presumptive diagnosis of passive reflux can be made if, after urination, the patient has dilatation of the cavities of the maxillary sinus for half an hour or more (provided that the patient is normally hydrated). Traditionally, ultrasound diagnosis of reflux is confirmed by ureterocystography.

The expansion of the pyelocaliceal system does not always indicate obstructive uropathy. Options for the development of the extrarenal pelvis have already been mentioned on the previous page. In addition, prominent vessels leading to the hypoechoic medullary pyramids may be visible at the renal hilum. They may be mistaken for elements of the collecting system, but these vessels have a more delicate appearance and are not as distended as is the case with obstruction and expansion of the collecting system. Pyeloectasia is an ampullary dilatation of the renal pelvis with increased urine excretion. It is characterized by the following sonographic signs:

Triangular or cone-shaped hypoechoic formation in the region of the renal pelvis

· No cup expansion.

· Lack of dilatation of the ureter.

· CDI: absence of vessels.

Rice. 20. Pyeelectasia (P), CD. A large renal vein can be excluded from the list of diseases with which this condition should be differentiated.

Color Doppler can easily determine whether these structures are blood vessels with rapid blood flow or a collecting system filled with static urine. Blood vessels appear as color-coded structures, the color of which depends on the direction and speed of blood flow, while slow-moving urine in the collecting system remains black. A similar principle of flow rate differentiation can be used to distinguish renal sinus cysts, which do not require any treatment, from obstructive dilation of the renal pelvis, which should be observed or treated. Of course, these two states can exist simultaneously.

The literature discusses vasorenal and vasourethral conflicts that cause the presence of Frayly syndrome, manifested by compression of the calyces by vessels, anomalies of the vascular-ureteric relationship (pelvic-ureteric segment, retrocaval or retroiliac location of the ureter, etc.) with the development of hydrocalycosis, pyelocalicoectasia, ureterocalicopyelectasia.

Distinguishing these manifestations from first (mild) degree obstructive dilatation can be very difficult.

There is a distinction between obstruction “from within” the pyelocaliceal system of the renal cavities. The most common obstruction is a calculus, less often a salt or inflammatory embolus, a tumor. Obstruction occurs with various anomalies of the urinary system - ureteral strictures, stenoses of the ureteropelvic segment, high ureteral discharge, ureterocele and etc. Below the site of obstruction, the urinary tract is not visualized against the background of perinephric tissue. Obstruction of the urinary system “from the outside” is most often caused by pathology of the retroperitoneal space. These are tumor lesions of the retroperitoneal lymph nodes, primary and metastatic tumors of the retroperitoneal space, retroperitoneal fibrosis, tumors of adjacent organs. .

With the first (mild) degree of obstructive dilatation, the renal pelvis expands, but without stretching the calyces and visible thinning of the parenchyma.

Rice. 21. Disturbance of urine outflow, first stage: a - the pelvis is filled with liquid (^), the necks of the cups are not yet stretched;

The second (moderate) degree of obstructive dilatation causes an increase in the filling of the cups, as well as a decrease in the thickness of the parenchyma. The bright central echo complex becomes sparse and eventually disappears.

Rice. 22. Impaired urine outflow, second stage. Expansion of the necks of the cups.

The third (severe) degree of obstructive dilatation is characterized by severe atrophy of the parenchyma due to compression and the presence of a cystically dilated pelvis.

Rice. 23. Violation of urine outflow, third stage. Cystic dilated pelvis (^), stretched calyces, significant thinning of the parenchyma.

At the fourth (terminal) stage of obstructive dilatation, the parenchyma is practically not visualized.

Rice. 24. Impaired urine outflow, terminal stage. Parenchyma is almost completely absent (^).

Sonography is not able to identify all causes of structural uropathy. Because in most cases the mid-ureter is obstructed by overlying gas, a ureteral stone, unless lodged in the pelvic, ureteric, or paravesical region (in the upper or lower third of the ureter), is usually not visualized. Less common causes of ureteral obstruction are bladder or uterine tumors, enlarged lymph nodes, and retroperitoneal fibrosis after radiation or idiopathic, as manifested by Ormond's disease. Latent obstruction may occur during pregnancy, due to ureteral atony or with urinary tract infection. In addition, the cause of ureteral obstruction may be overdistension of the bladder as a result of neurogenic disorders and prostatic hypertrophy. In these cases, an ultrasound examination should include an examination of the bladder and a search for an enlarged prostate gland in men.

Kidney infarction

Embolism or stenosis of the renal artery can cause focal renal infarctions. Clinical manifestations: flank pain, hematuria and proteinuria; fever, leukocytosis; nausea, vomiting Renal failure with oliguria may develop. After a few days, arterial hypertension appears.

In case of renal infarction, its shape corresponds to the location of the vessels in the parenchyma of the spleen and is characterized by a wide base at the surface of the kidney and narrowing towards the hilum.

Ultrasound data:

· Segmental occlusion of the renal artery within 48 hours is manifested by the appearance of a zone of sharply reduced echogenicity, corresponding to the infarction zone. In the acute stage of renal artery embolism, the kidney may have a normal echo structure; a wedge-shaped hypoechoic area, the apex of which is directed towards the renal pelvis, can be determined.

· From 7 to 21 days after a heart attack, a decrease in the infarction area is observed, the boundaries of the infarction area become clearer. An echogenic triangular scar is formed, as a result of which a depression is formed on the surface of the kidney, and the layer of parenchyma decreases.

· In hemorrhagic infarction as a result of thrombosis of the renal artery, hemorrhage into the parenchyma leads to the appearance of a heterogeneous echogenic formation of irregular shape.

· CDE shows absence of blood flow in the renal artery and sometimes a wedge-shaped parenchymal perfusion defect.

· At later stages, scanning reveals a decrease in the size of the kidney. By the 35th day after a heart attack, the defined zone sharply decreases, its echogenicity increases. The remaining scars are echogenic and similar to kidney stones. They can be distinguished by the form of localization.

Rice. 25 a, b Renal infarction, a Wedge-shaped, well-demarcated hypoechoic area. b Enlargement: the presence of a triangular avascular zone confirms the diagnosis of infarction. The patient was admitted with complaints of pain in the side.

Accuracy of ultrasound diagnostics: a reliable diagnosis of a fresh renal infarction is impossible without the use of CDE, the accuracy of which reaches 85%. The diagnosis can be confirmed by ultrasound using echo contrast agents or by CT angiography.

Urolithiasis

Currently, echography is the most accurate method of non-invasive diagnosis of nephrolithiasis. An important advantage of echography is the ability to visualize stones of any chemical composition, including X-ray negative uric acid stones. At the same time, detecting stones in the kidneys (nephrolithiasis) is much more difficult than in the gall bladder, since echogenic kidney stones are often located within an equally echogenic collecting system and do not provide any echo signals to distinguish them from surrounding structures. Difficulties in ultrasound diagnostics of stones arise when the stone size is small (3-4 mm). In the absence of dilatation, it is most important to detect the acoustic shadow of stones or calcifications, such as in hyperparathyroidism.

Stones in the dilated collecting system are a remarkable exception because they are clearly visible as echogenic structures in echo-negative urine. The stone causing the obstruction is clearly visualized against the background of fluid in the collecting system

Rice. 26. Hepatic pelvis stone. The hepatic pelvis is hypoechoic and dilated. A stone with a high-amplitude echo (arrow) and a dorsal acoustic shadow (S) is found in the area of the ureteropelvic junction. K - kidney.

Depending on their composition, kidney stones can either conduct ultrasound completely or reflect it so much that only the immediate surface, in the form of an echogenic cup, is visible.

In ultrasound practice, there is a significant overdiagnosis of stones and sand in the kidney. This is due to incorrect interpretation of the image of the renal sinus in the presence of small echo-positive structures in it. Differential diagnosis is made with arcuate arteries between the renal cortex and medullary pyramids (bright echo without shadow), vascular calcifications in diabetic patients and calcified foci of fibrosis after renal tuberculosis. Calcifications in the vascular wall are characterized by the presence of two linear hyperechoic structures located on both sides of the formation. Finally, papillary calcifications may occur after long-term use of phenacetin. Calcification of the pyramidal papilla is characterized by its location in the projection of the pyramidal papilla.

Fig.27. a, b. a Renal pelvic stone (not causing obstruction): a hyperechoic stone with a distal acoustic shadow (S; flicker artifact helps confirm the diagnosis of stones), b Diabetic papillary apical calcification: a bright echo at the apex of the medullary pyramid (arrow) c incomplete acoustic shadow (S).

The calculus is characterized by a rounded shape and a fairly clear acoustic shadow. However, all these differences very often do not allow differentiating hyperechoic structures against the background of renal sinus tissue. To clarify the nature of the existing hyperechoic structures, it is recommended to conduct a pharmacoechographic test with Lasix. If this hyperechoic structure is a calculus, then it will be located within the pelvicalyceal system, dilated with polyuria. In this case, the acoustic “shadow” from a small stone surrounded by liquid may be absent

Fig.28. a-s. a Photograph of the right kidney in a high transverse plane (K). Posterior to the artery, a dilated renal pelvis (R) is determined in the absence of dilation of the proximal part of the ureter. VC - inferior vena cava. b, c Dilatation of the pyelocaliceal system in a patient with flank pain. Suspicion of biliary colic, b Dilated calyx (CA) communicating with a dilated and obstructed renal pelvis (PY). c A proximal ureteral stone causing obstructive dilatation of the calyces. The image reveals anechoic formations in the central echo complex. The upper formation is an expanded neck of the calyx. A widening of the neck of the cup greater than 5 mm (here 11 mm) indicates obstruction. The lower formation is an enlarged renal pelvis.

Large staghorn stones are difficult to diagnose if they cast a distal shadow and, due to their echogenicity, may be mistaken for a central echogenic complex.

If kidney stones dislodge and pass from the intrarenal collecting system into the ureter, they may, depending on their size, pass into the bladder asymptomatically or with colic, or become lodged and cause ureteral obstruction. Clinical signs of urolithiasis: acute, severe attacks of abdominal pain caused by a kidney stone or, in rare cases, a blood clot. The release of urine into the perinephric space leads to the formation of urinoma.

Rice. 29. a, b Renal colic against the background of a stone at the ureteropelvic junction. a Hydronephrotic kidney (K) with a dilated, fluid-filled renal pelvis and transudate (urinoma, FL). b Ureteropelvic junction stone (arrow, U) and dilated renal pelvis (P). The image was taken in the superior oblique longitudinal plane of the abdominal cavity along the right ureter.

There is a widespread belief among ultrasound doctors that it is impossible to visualize stones in the ureter. Indeed, the ureter at a normal level of diuresis is practically not differentiated from the retroperitoneal tissue. However, in the presence of urostasis or artificial polyuria, visualization of the ureter is possible. With pronounced dilatations of the ureter (more than 0.7-0.8 cm), the ureter is visualized all the way to the bladder in a patient of any size.

Fig.30. a, b Urolithiasis with a stone (arrow) located in the prevesical part of the ureter (U). a B-mode image: high-amplitude echo with incomplete acoustic shadow. An image in the lower transverse oblique plane of the abdominal cavity, b CDE, performed 4 days later: a stone at the orifice of the ureter, not causing its obstruction; stream of urine (red color); faint artifact of "flickering" in the acoustic shadow of the stone.

The ureter is better visualized when examined in the frontal plane with the patient in the lateral position. With minor dilatations (the ureter is visualized as a hypoechoic thin strip of 4-6 mm), as a rule, visualization of the prevesical section is very difficult, since after “crossing” with the iliac vessels, the ureter deviates quite sharply backwards, towards the posterior wall of the bladder. Therefore, with a large filling of the bladder, visualization of the prevesical section of the ureter is extremely difficult, because under such conditions, the ureter deviates even more posteriorly. When examining the prevesical section of the ureter, it can be recommended to force diuresis as much as possible (to fill the ureter more tightly with liquid) and not to fill the bladder too much - up to a maximum of 100-150 ml. The bladder is slightly full.

In addition to diagnosing obstructive uropathy, sonography helps exclude other causes of abdominal pain, such as pancreatitis, colitis, fluid accumulation

Fig. 31 a, b Common causes of chronic urinary tract obstruction (UUT). a Metastatic tumor in the pelvis (ovary, uterus; in this image: rectal carcinoma), b Bladder carcinoma (urothelial carcinoma, arrows), often localized near the ureteral orifice. The differential diagnosis includes metastatic prostate carcinoma. U - ureter, IA - iliac artery, B - bladder.

Kidney tumors

Unlike fluid-filled cysts, kidney tumors have internal echoes and little or no acoustic enhancement is detected behind them.

Organ-specific benign tumors of the kidney include adenomas (or oncocytomas). Angiomyolipomas, urothelial papillomas. Benign kidney tumors (fibromas, adenomas, hemangiomas) are quite rare and do not have a universal sonographic morphology.

Only angiomyolipoma, a benign mixed tumor that includes blood vessels, muscle and fatty tissue, has specific sonographic features at an early stage that make it possible to distinguish it from a malignant process. Small angiomyolipomas have the same echogenicity as the central echo complex and are clearly circumscribed. However, Derchi L. et al. (1992) described a case of renal adenocarcinoma giving almost identical ultrasound semiotics. With increasing size, angiomyolipoma becomes heterogeneous, which complicates its differentiation from malignant tumors. Angiomyolipoma has a slow (several mm per year) non-invasive growth. Small angiomyolipomas of the parenchyma are echographically similar to calcifications in the parenchyma, however, in the presence of angiomyolipoma, both the anterior and posterior contours of the formation are visualized equally well. If calcification is present, ultrasonic signals are reflected from the front surface of the formation, and then an acoustic shadow is determined. The contour of the formation more distant from the scanning surface of the sensor is not visualized. Angiomyolipomas of the renal sinus are detected sonographically only when the tumor size is sufficiently large and in the presence of deformation of the central echo complex. Angiomyolipomas can be multiple in nature. Most often, multiple angiomyolipomas in combination with multiple cysts are determined in tuberous sclerosis, a congenital disease characterized by the development of specific granulomas in the brain, with the clinical picture of oligophrenia and epilepsy, as well as a multi-organ tumor process.

A small renal cell tumor (hypernephroma) is often isoechoic compared with the rest of the renal parenchyma. Only with further growth does hypernephroma become heterogeneous and occupy space with bulging of the kidney contour.

Fig.32. Hypernephroma. A large tumor of the upper pole of the kidney with hypoechoic and hyperechoic inclusions.

If hypernephroma is detected, it is necessary to carefully examine the renal veins, the corresponding locations of the lymph nodes, and the contralateral kidney to identify neoplastic changes. In approximately 5% of cases, renal cell carcinoma has bilateral growth; an advanced tumor can grow into the vessels and spread along the renal and inferior vena cava. If the tumor grows through the capsule and spreads to the adjacent psoas muscle, the kidney loses its ability to breathe.

Renal leiomyomas are quite rare. It is assumed that renal leiomyomas develop from the muscular elements of the wall of the vessels of the renal sinus. Echographically, leiomyomas are presented as a solid volumetric structure with clear, even contours of lower echogenicity than the renal parenchyma.

Renal lymphomas cause diffuse enlargement of the organ with diffuse damage to the parenchyma with multiple small hypoechoic formations with an indistinct contour, either visualized as hypo- or visualized as hypo- and anechoic large lesions of a rounded shape with a thin capsule and clear distal pseudoenhancement. In this case, a differential diagnosis with simple renal cysts is necessary. Kidney lymphoma in most cases is an organ manifestation of a general disease and usually appears in the later stages of the process. Often at this stage of the disease, packages of altered lymph nodes are visualized.

Clear cell adenoma cannot be differentiated sonographically from kidney cancer. Unfortunately, the diagnosis of this benign tumor is often established only at autopsy, after removal of the organ. When examined by ultrasound, the cystic form of adenoma has the shape and structure of a honeycomb. In this case, it is necessary to carry out a differential diagnosis with a multilocular cyst and a cystic form of hypernephroid cancer.

The left adrenal gland lies anterior and medial (not superior) to the upper pole of the kidney. The right adrenal gland is positioned posterior to the pole, towards the inferior vena cava. In adults, the adrenal glands are not visible or sometimes faintly visible in the perinephric tissue. Hormone-producing adrenal tumors, such as adenoma in Conn syndrome or hyperplasia in Cushing syndrome, are usually too small to be detected by sonography. Only clinically significant pheochromocytoma, usually already several centimeters in diameter, can be detected sonographically in 90% of cases. Sonography is more important for identifying metastases in the adrenal glands.

Metastases are usually seen as hypoechoic lesions between the upper pole of the kidney and the spleen or inferior surface of the liver, respectively, and should be differentiated from atypical renal cysts. Hematogenous spread of metastases is due to strong vascularization of the adrenal glands and can occur in bronchogenic cancer, as well as in breast and kidney cancer. Whether a mass in the adrenal gland is malignant or not cannot be decided based on its echogenicity. Before performing a fine-needle biopsy, pheochromocytoma should be excluded to avoid a hypertensive crisis.

Sonography of patients undergoing kidney transplantation

Kidney grafts can be in any of the iliac fossae and connected to the iliac vessels.

Typically, the graft is placed in the iliac fossa on the contralateral side of the recipient. The kidney is rotated in such a way that the posterior surface of the kidney faces anteriorly, the anterior surface faces posteriorly. The renal vein anastomoses with the external iliac artery, the renal vein with the internal iliac vein. The orientation of the graft hilum is opposite to that of the normal kidney. The transplanted kidney's ureter is connected to the bladder or, rarely, to the recipient's ureter. The kidney is located in an oblique direction, retroperitoneally, in front of the m. psoas and iliac veins.

Like dystopic kidneys, grafts are examined in two projections, but the probe is placed laterally in the lower abdomen. Because the transplanted kidney is located directly behind the abdominal wall, bowel gas will not interfere with the examination.

Early diagnosis of graft rejection or other complications is extremely important. The norm for a kidney transplant after surgery is an increase in size of up to 20%.

A very important indicator for identifying echographic signs of graft pathology is the ratio of the anterior-posterior size of the kidney to its length. Normally, this ratio is 0.3-0.54, while the anterior-posterior size of the kidney does not exceed 5.5 cm. Accordingly, the transverse section of the transplanted kidney normally retains a bean-shaped or oval shape. To accurately assess the size of the kidney graft, first examine it in a longitudinal section and select the position of the sensor so that the length of the organ is maximized. The sensor is then turned slightly. This two-step technique provides confidence that the length measurements are not underestimated, and this can lead to an erroneous conclusion about an increase in volume (simplified formula: vol = AxB Cx0.5) during subsequent control studies.

Compared with normal kidneys, the graft cortex appears thicker, and the echogenicity of the parenchyma is reduced so much that the medullary pyramids become clearly visible. Progressive inflammatory infiltration should be excluded by conducting a series of control ultrasound examinations over a short period of time immediately in the postoperative period. In the future, the kidney graft should be assessed for the clarity of its outer contour and the boundary between the parenchyma and the collecting system.

A dilated renal pelvis or slightly dilated collecting system (first stage) may be due to functional failure of the renal graft and does not require intervention. Normally, in the postoperative period, moderate dilatation of the graft's CL is acceptable, apparently associated with edema of the ureteroneocystoanastomosis. However, this dilation should not reach significant proportions. Urine distension should be documented.

Fig. 33 Renal allograft (K) in the right side of the lower abdominal cavity. Arrows: dilated, fluid-filled collecting system. C - renal columns, MR - hypoechoic pyramids of the medulla

Complications of a transplanted kidney include acute tubular necrosis, acute graft rejection, obstructive processes, vascular complications, the formation of various leaks, hematomas, abscesses as a result of anastomotic failure and rejection crises.

An unclear boundary between the parenchyma and the collecting system and a slight increase in volume may be warning signs of incipient rejection. Acute graft rejection develops within the first few weeks after transplantation (however, the use of immunosuppression can significantly change the timing of acute rejection). Cases of the development of acute rejection up to 5 years after transplantation have been described. Histologically, acute rejection reveals cellular mononuclear infiltration and swelling of the renal interstitium. The vascular bed changes significantly: the wall of blood vessels (arteries and arteriopes) sharply thickens with the development of hemorrhages. Heart attacks, thrombosis. Echographically, the graft increases in size, mainly due to its anterior-posterior size, while in transverse scanning the slice shape becomes rounded. There is a rapid increase in the volume of the kidney graft (more than 25% in two weeks). The ratio of the anterior-posterior size to the length of the kidney exceeds 0.55. The anterior-posterior size of the kidney increases by more than 5.5 cm. There is an increase in the cross-sectional area of the pyramids, which corresponds to interstitial peritubular edema. The echogenicity and cross-sectional area of the central echo complex corresponding to the renal sinus are reduced due to a decrease in the number of fat cells in the renal sinus. Hypo- and anechoic areas appear in the parenchyma, corresponding to areas of edema, hemorrhage, and necrosis. In general, the graft cortex becomes more echogenic due to cellular infiltration. To ensure a valid comparison, reproducible longitudinal and cross sections should be selected for measurement and documentation. After transplantation, the intensity of immunosuppressive therapy is gradually reduced, and the time intervals between control ultrasound examinations can be increased.

Acute tubular necrosis develops in almost 50% of transplanted kidneys. Pathogenetic factors in the development of acute tubular necrosis of the graft are disseminated intravascular coagulation syndrome and hypotension that occur during transplant storage before surgery. Clinically, acute tubular necrosis is manifested by the appearance of symptoms of acute renal failure. Very rarely, echographically, in acute tubular necrosis, an increase in pyramids and a decrease in their echogenicity are noted. Most often, acute tubular necrosis does not manifest itself echographically, but the absence of echographic changes during the development of acute renal failure of the graft does not “remove” the diagnosis of acute tubular necrosis.

Urinary tract obstruction is an equally common complication and, depending on severity, may require placement of a temporary drain to prevent damage to the renal parenchyma. Measurements of the pelvis and cross-sections should be taken so that subsequent studies do not miss any dynamics requiring therapeutic intervention. The phenomena of dilatation of the urinary tract develop as a result of obstruction of the ureter “from the inside” by a blood clot, a stone, as a result of the formation of a stricture, as well as compression of the ureter by liquid streaks formed near the graft due to anastomotic failure. The degree of dilatation of the urinary tract, determined by ultrasound, in such cases is very significant

Lymphocele can develop as a complication of kidney transplantation. Typically, a lymphocele is found between the lower pole of the kidney graft and the bladder. But it can be anywhere near the transplant. Fluid leaks are most often formed as a result of anastomotic failure, with acute graft rejection. Hematomas, lymphoid leaks, seromas, urinomas are detected. Fluid leaks can fester and form abscesses. More often, the echographic picture of the leak does not allow differentiating its composition.

Vascular reactions are defined as venous thrombosis, complete or partial arterial occlusion. In acute venous thrombosis, the kidney quickly and sharply increases in size, the parenchymal cortex becomes thicker, its echogenicity sharply decreases, and corticomedullary differentiation disappears. Multiple hypoechoic areas appear in the renal parenchyma, corresponding to areas of hemorrhage. The changes are similar to those seen in acute rejection, so in conclusion it is more correct to make two presumptive diagnoses. Occlusion of the main trunk of the renal artery, as a rule, does not produce any echographic changes. Measuring the resistivity index (RI) of the renal blood vessels during Doppler ultrasound provides additional information about the condition of the kidney graft. Recently, Doppler examination of graft vessels has been considered very promising to determine rejection crises, determine occlusion of renal vessels, as well as the specifics of morphological changes that occur during graft pathology. A marked increase in vascular resistance is observed during a crisis of kidney transplant rejection. In this case, there is a moderate decrease in the maximum systolic blood flow velocity and a significant decrease or disappearance of diastolic flow. A pronounced rejection reaction is characterized by a significant decrease in systolic blood flow, a virtual absence of blood flow in the diastole phase, and an increase in acceleration time. A rejection reaction of weak or moderate severity is characterized by a moderate decrease in systolic blood flow velocity (mainly in the interlobular arteries), a decrease in diastolic blood flow with a gentle slope throughout the entire diastole.