Bleeding is considered a dangerous symptom in diseases of the gastrointestinal tract, which means that it requires immediate medical attention. The pronounced red color of feces leaves no doubt about the presence of pathology, but the latent course progresses for a long time and imperceptibly, which leads to severe complications. Visually, abnormal inclusions are not detected, therefore, it becomes possible to make a correct diagnosis only after laboratory tests.

The essence of the analysis

A fecal occult blood test shows the presence of blood particles that cannot be seen under a microscope during a coprogram. Such a study is one of the most common and allows timely detection of bleeding from the organs of the gastrointestinal tract.

Violations of the integrity of the mucosa can occur in the upper or lower digestive system. In the first case, blood particles undergo biochemical processes and, getting into the feces, acquire a burgundy or brown color. If tissue damage has occurred in the large intestine, the detected discharge remains scarlet.

In severe diseases, such as malignant, occult blood is the only symptom of the initial stage. Timely diagnosis makes it possible to start the right treatment and preserve the health of the patient.

When an examination is ordered

The analysis is carried out when a life-threatening disease is suspected, or to identify the cause of pathological conditions associated with metabolic disorders. Indications for the study of feces for blood are as follows:

• Helminthiasis.
• Persistent vomiting, heartburn, or nausea.
• Gastric ulcer.
• Abdominal pain of unknown origin.
• Liquid stool.
• Excessive weight loss.
• Diagnosis of the state of the mucous organs of the gastrointestinal tract.
• Digestive disorders.

In addition to all these situations, doctors prescribe a stool study at their discretion. It is better for the patient to agree with the doctor and conduct an additional analysis, as it will help to make the most accurate diagnosis. Thus, the reaction to occult blood is necessary to obtain information about the presence of damage to the walls of the digestive organs.

Types of occult blood tests

Modern research methods are more accurate and revealing than those used a few years ago. There are two methods to help detect occult blood.

Benzidine test

It was popular for a long time, as it made it possible to determine even low concentrations of blood components. The principle of action is based on the detection of hemoglobin, the main component of red blood cells. To do this, a chemical reaction is used, as a result of which the iron in the heme is oxidized by hydrogen peroxide and becomes blue.

The disadvantage of the method is its non-specificity. That is, a positive reaction is obtained when exposed to an iron atom of any origin, even animal and vegetable. Because of this, the patient needs to undergo special training, where it is important to follow a certain diet.

Immunochemical analysis

It is a more accurate study. It is prescribed both independently and in addition to other methods to clarify their results. The principle of operation is different from the previous one. Here, the basis is the determination of the concentration of specific antibodies that are produced in humans in response to antigens. The method is more often used in pathologies of infectious genesis. Among the shortcomings, the duration of execution is noted - the final results and the diagnosis become known only after 1-2 weeks.

No type of analysis involves internal interference or additional damage. The high sensitivity of the reagents requires some preparation of the patient in order for the results to be reliable.

Preparation for analysis

• Drugs that can affect the results are canceled 1 week before the analysis.
• The day before the study, it is necessary to exclude possible damage to the oral cavity, including when brushing with a hard toothbrush or eating solid food.
• Women should be tested during the absence of menstruation.
• A few days before taking the biomaterial, you need to follow a diet. You can not eat foods containing iron (meat, fish, tomato, beets). With the immunochemical method, restrictions may not be observed.
• Previously, it is not allowed to carry out artificial emptying with enemas and laxatives (even based on herbal ingredients).

How to properly collect feces?

The rules for taking biomaterial are as important as preparing for analysis. The test sample must be fresh, so the stool is delivered to the laboratory as quickly as possible.

To properly pass the analysis, you need to be guided by the following recommendations:

• Prepare a container for collecting biomaterial. It is better to use special jars that are sold in pharmacies and already contain spatulas for sampling.
• After defecation, collect dry stool residue without water and urine, which may accidentally fall on them. It is better to do this in the morning so that the biomaterial is immediately taken to the laboratory.
• The amount required for the study is 3 fragments of feces, which are taken from different sites. To do this, use a teaspoon or spatula from a pharmacy container.
• The biomaterial must be delivered to the laboratory not later than 3 hours. Until then and during transport, it is recommended to keep the material sample in a refrigerator.

Deciphering analyzes

The results of the analyzes are compared with indicators that are considered normal. Doctors allow up to 2 ml of blood to enter the intestines daily. If the detected particles are greater than this number, the result is considered positive and the doctor has reason to suspect internal bleeding. When occult blood is not detected or its concentration is less than 1 mg per 1 g of feces, the results of the study are considered negative. Doctors take into account only elevated values.

Due to improper preparation for the study, the result is always erroneous. Doctors note that data distortions occur both in the direction of positive results and negative ones. In order not to doubt the obtained indicators, it is recommended to repeat the study even without any reason.

It is known that in some diseases, pathological bleeding is observed not constantly, but periodically, and this makes it difficult to detect. If the preliminary diagnosis is known, for example, intestinal polyps, then the absence of hemoglobin will raise doubts and a second analysis will be required. That is why doctors prescribe several types of examinations for diagnosing a patient - laboratory, instrumental.

What does a positive result mean?

An increased amount of hemoglobin in the feces often confirms damage to the digestive tract and the presence of pathologies. A positive analysis suggests one of the following conditions:

• Crohn's disease.
• Bleeding caused by varicose veins of the esophagus.
• Malignancy or polyps.
• Nonspecific ulcerative colitis.
• Fissure of the anus, mechanical damage due to constipation or hemorrhoids.
• Oral problems.
• Helminth infestation.
• Ulcerative lesions of the stomach or duodenum.

Since a positive result suggests serious pathology, the patient should verify the reliability of the data obtained and repeat the analysis. Small errors in nutrition or accidental damage to the oral cavity lead to false readings, and therefore it is important to properly prepare for the first examination.

The method of re-examination is chosen by the doctor - this may be a second laboratory analysis or examination of the intestine using an endoscope. Often, when confirmation of the presence of occult blood is obtained, especially by immunochemical method, the patient is also recommended to do a colonoscopy.

An additional examination of the intestine will help confirm or refute the presence of bleeding polyps or other neoplasms. The feasibility of the double examination algorithm has been proven in screening programs. Thanks to this approach, the mortality of patients was reduced by 25%.

Few, having emptied their intestines, think that the characteristics of this biomaterial can be used to judge the presence of such serious pathologies as stomach ulcers, Crohn's disease, polyps and malignant neoplasms of the intestine.

To identify them, you will need to take fecal occult blood tests. Diagnosis does not take much time, is painless and allows you to suspect the development of ailments even at an early stage.

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Fecal occult blood test - what is it?

In some pathologies of the rectum, for example, internal hemorrhoids or anal fissure, inclusions of scarlet blood are visible in the feces with the naked eye.

However, when bleeding occurs in the small intestine, a different picture is observed. Blood components are digested by enzymes, mixed with feces and excreted. In this case, the blood loses its scarlet color. If the bleeding in the small intestine is severe enough, the feces may turn black - this is an alarm signal. However, such a clinical picture does not always develop.

More often, the components of digested blood are mixed with feces and become indistinguishable to the naked eye. You can't even see them with a microscope. It is this blood that is called latent.

It can be found in feces in the following ways:

• guaiac or benzidine test;
• immunological method;
• fluorescent analysis.

Chemical samples

Historically, reactions with guaiac and benzidine were the first to appear in the arsenal of diagnostic methods. The principle of their action is based on the fact that blood hemoglobin is a strong oxidizing agent. Reacting with substances such as benzidine and guaiac, it changes their color. The more occult blood in the feces, the more intense and faster the color of the reagents changes.

The disadvantage of this method is the relatively low sensitivity of these samples. The reaction with benzidine reveals a daily blood loss of at least 15 ml. Normally, a person can lose up to 1 ml of blood in 24 hours during bowel movements.

Slight increases in this indicator can warn of the first stages of various pathologies of the gastrointestinal tract, but the benzidine test cannot detect them.

The reaction with guaiac is more accurate, but even it is able to warn only 50% of patients about incipient colon cancer. In the case of colorectal oncopathology, the sensitivity of the method does not exceed 30%.

Both tests may give false positive results. Most often this is due to improper preparation for analysis.

Method of immunochromatography

More perfect immunochemical analysis of feces. It is convenient, standardized and simple. Immunochromatographic detection of occult blood resembles the procedure for performing a pregnancy test.

Monoclonal antibodies are used to perform this fecal analysis. The prepared biomaterial sample is applied to the test strip.

The monoclonal particles bind to human hemoglobin to form a colored complex. Further, it is captured by other antibodies localized in the control region, and two marks appear on the test strip if the concentration of occult blood is higher than normal. Otherwise, one bar is rendered.

The immunochemical method is highly sensitive and does not require special preparation. It allows you to detect weak bleeding in the early stages of colon cancer in 97% of cases. However, the analysis is not suitable for diagnosing diseases that develop in the small intestine.

Fluorescence analysis

Fluorescence can also be used to detect hemoglobin breakdown products in feces. In this case, the biomaterial is processed in a special way, and its glow is recorded. It is known that porphyrin pigments, which are part of hemoglobin molecules, can be detected by fluorescence when the latter is destroyed.

This method is quite accurate, but if a person eats meat food the day before, animal hemoglobin will appear in his feces - this will cause a false result.

Recently, another approach to diagnostics has been developed. Human DNA is extracted from the feces selected for analysis and examined for changes characteristic of the tumor process.

When should I take a fecal occult blood test?

Obviously, the study is indicated when there are signs of disorders of the digestive system. The following symptoms should be the reason for the analysis:

• heartburn;
• stomach ache;
• change in the nature of the chair;
• nausea or vomiting that bothers you for a long time;
• mucus impurities in the feces;
• foamy inclusions.

In addition, an occult blood test should be performed annually for all persons over the age of 40 years. This is the best measure for the timely detection of inflammatory and especially oncological pathologies. The following clinical picture can warn about the development of a malignant process in the gastrointestinal tract:

• regular increase in body temperature for no apparent reason;
• loss of appetite;
• aversion to meat food;
• sudden loss of body weight;
• constipation;
• pain during defecation.

In addition, if bloody discharge visible to the naked eye appears in the stool from time to time, or the stool becomes black, you should not hesitate with the analysis. These signs warn of bleeding caused by polyps, tumors, erosions, or ulcers.

How to prepare for the analysis?

To pass a stool test for occult blood, special preparation will be required. Depending on which method or methods of research will be used, the patient will have to adhere to a certain regimen.

Diet

Chemical assays and fluorescent analysis are non-selective. They detect components of not only human, but also animal hemoglobin obtained from food. For this reason, before such an analysis of feces for occult blood, a diet is shown that implies a complete rejection of meat, fish, and poultry. Any by-products are also prohibited.

In addition, when preparing for a fecal occult blood test, you should not eat foods rich in iron:

• beans;
• pomegranate;
• bell pepper;
• tomatoes;
• spinach, parsley;
• apples;
• Brussels sprouts, broccoli;
• carrot.

If the study is carried out by immunochromatography, the need for a special diet disappears. Monoclonal antibodies bind exclusively to human hemoglobin and do not react to compounds of a different origin.

Medicines and medical procedures

Diets must be followed for at least 3 days before analysis. At this time, it is also important to completely stop taking iron preparations, ascorbic acid and all non-steroidal anti-inflammatory drugs (Aspirin, Ibuprofen, etc.).

During this period, you should refrain from any procedures that are theoretically capable of violating the integrity of the intestinal and stomach mucosa. You can not put enemas, undergo fibrogastroscopic examination, undergo irrigoscopy, sigmoidoscopy, colonoscopy. Even laxatives are banned. You need to stop taking them at least a week before the analysis.

From the moment of the last x-ray examination to the moment when the feces are collected for analysis, at least 3 days must pass.

Other Features

Some diagnostic methods are highly sensitive and can detect even minimal amounts of blood in the biomaterial. For this reason, in order to avoid false results, you should refrain from brushing your teeth on the eve of the analysis, because bleeding from the gums is not uncommon.

Women should not take feces for analysis during menstruation. Even nosebleeds that occurred the day before can distort the results. In addition, when taking the material, it is important to ensure that urine does not get into it.

Features of the collection of biomaterial

Feces for analysis are taken into a sterile special container. You can buy it at a pharmacy.

• It is necessary to collect biomaterial from different parts of the feces: 2-3 fragments.

After that, it is important to place the container in the refrigerator and deliver it to the laboratory within 3 hours.

The less time that has passed since collection, the better.

Deciphering the analysis of feces for occult blood

Immunochemical analysis and samples with benzidine and guaiac are semi-quantitative methods for the determination of occult blood. The first diagnosticum gives an answer to the question: does the concentration of hemoglobin in the stool sample exceed the normal value?

• If the laboratory assistant or patient at home sees 2 marks on the test strip, the answer is yes. One control is negative.

When setting samples with guaiac and benzidine, the intensity and speed of staining of the reagents are evaluated. The reaction can be of 5 types:

• negative (no color change);
• weakly positive (+);
• positive (++);
• positive (+++);
• sharply positive (++++).

Fluorescent analysis is a quantitative method. It is not sensitive at concentrations of porphyrins up to 2 mg/g of biomaterial. But when their content in 1 g of feces is equal to or exceeds 4 mg, a pathology is diagnosed. The test is also able to reveal borderline values: from 2 to 4 mg.

The analysis is positive, what does it mean?

Having received the conclusion that occult blood was detected in the stool sample, you should not panic. In addition to pathological conditions, the result can be positive in the following cases:

• non-compliance with the rules of preparation for analysis;
• nose bleed;
• menstruation;
• stomatitis;
• periodontitis.

If occult blood is detected, the doctor will refer the patient for additional examination. Colonoscopy will allow you to assess the condition of the mucous membrane of the large intestine, to identify foci of altered cells (polyps and tumors).

If necessary, a biopsy of pathological material is performed. In addition to colonoscopy, computed tomography and magnetic resonance imaging (CT and MRI) are used.

A positive analysis of feces for occult blood occurs with helminthiases, ulcers of the stomach and small intestine, Crohn's disease, colitis, intestinal tuberculosis, hemorrhoids, anal fissures, as well as with polyps and tumors.

The latter may not cause permanent bleeding and can be detected only with a systematic diagnosis. It is desirable to conduct at least 3 consecutive studies.

But hidden blood can indicate no less formidable diagnoses, and when the disease is still at an early stage of development, and the chances of a successful recovery are much greater. That is why, in the presence of the first suspicious symptoms, it is necessary to obtain qualified medical advice and pass all the necessary tests. And people over the age of 50 with a history of colorectal cancer should have a fecal occult blood test every year, as this simple measure can save lives in some cases.

Many pathologies of the gastrointestinal tract, including ulcerative colitis and malignant tumors of the intestine, for the time being do not bother the patient with severe discomfort. But the destruction of healthy tissues is already taking place, therefore, blood is released, which cannot yet be visually detected in the feces, but it is quite possible to do this with the help of special laboratory samples. Today we will tell you what a fecal occult blood test shows, how to prepare for the study and what diet you need to follow, how to collect and donate material correctly, what a positive and negative result indicates, in which cases it can be false, and what methods of determining occult blood in the feces are most accurate.

Hidden blood in stool - what does it mean?

A certain amount of blood can normally be present in the feces - no more than 2 mg of hemoglobin per 1 g of feces, at such a maximum concentration it turns out that a healthy person loses up to 2 ml of blood with feces per day. If the bleeding becomes more intense, the color of the feces changes, and its shade indicates the localization of the problem: the darker, the higher. For example, with a bleeding ulcer of the stomach or duodenum, the feces become black, tarry (melena), if the cause lies in an exacerbated ulcer, the stool will become burgundy, and bleeding polyps, hemorrhoids and malignant neoplasms in the rectum lead to the appearance of scarlet streaks and spots on stool masses. Such signs cannot go unnoticed and should be the reason for immediate medical attention.

Occult blood in the stool is blood that cannot be detected either by visual or microscopic examination of stools. Only a fecal occult blood test allows you to find it - a positive result indicates the presence of occult gastrointestinal bleeding and requires a mandatory additional examination of the patient.

Who needs a fecal occult blood test?

This kind of research is assigned in the following cases:

Persistent periodic pain in any part of the abdomen, as well as in the right or left hypochondrium;

Discomfort and soreness during or after a bowel movement;

Sensation of the presence of a foreign body in the rectum;

Loss of appetite, a sharp decrease in body weight for no apparent reason;

Nausea, vomiting, belching, heartburn, bad taste in the mouth;

Diagnosed pathologies of the gastrointestinal tract: Crohn's disease, intestinal polyposis, diverticulosis, esophageal varicose veins, helminthiasis, and so on - the study is performed to determine the stage of the disease or control the course of treatment;

Alarming results from other previous examinations, such as a general or biochemical blood test;

Prevention of bowel cancer over the age of 40-50 years in patients with unfavorable heredity.

Preparation, diet, collection and delivery of analysis

It makes sense to conduct a study on occult blood in the feces only if the rules of preliminary preparation are carefully observed, otherwise the probability of obtaining a false result will be very high.

Let's start in order:

Temporarily postpone analysis it is necessary until the following circumstances are eliminated - periodontal disease, epistaxis, menstruation, hematuria, exacerbation of hemorrhoids, recent diagnostic manipulation with the intestines (colonoscopy, sigmoidoscopy), anal sex. All these factors are likely to lead to a distortion of the results of the study, which means that it is necessary to solve the existing problem or wait a few days, depending on the situation;

One week before analysis you should refuse to take any medications that undesirably affect the composition of feces, namely, NSAIDs (aspirin, ibuprofen, naproxen), barbiturates, anticoagulants, intestinal motility stimulants, ascorbic acid, drugs and dietary supplements containing iron. If you are constantly taking any medications, and you are not sure that they will not affect the results of the study, it is better to consult your doctor in advance;

Three days before analysis you need to start dieting - a fecal occult blood test is almost always carried out using laboratory samples that are sensitive to the composition of the food consumed by the patient. Therefore, you will have to temporarily give up any meat, poultry, fish and offal - that is, everything that may not contain your blood. In addition, it is recommended to exclude from the menu some beans, vegetables, fruits and berries that are rich in iron and vitamin C or strongly affect intestinal motility - for example, apples, celery, cranberries, oranges, spinach, nuts, cabbage, tomatoes, carrots, beets, beans, soybeans and lentils;

12 hours before analysis it is necessary to put down the toothbrush and stop eating hard foods that can injure the gums and lead to blood from the mouth into the digestive tract.

Successful occult blood test = preparation + diet, remember this!

So, the preparatory stage is over, it is time to collect material for research and take it to the laboratory:

Early in the morning, before breakfast, make an external toilet of the intimate area using ordinary soap, rinse thoroughly and dry;

Defecate in a pre-prepared clean container. The process should occur naturally, without the use of enemas or laxatives. You can't take a stool sample from the toilet. An analysis of feces for occult blood in a child is taken from a well-washed pot, from a diaper or oilcloth;

For the collection and transportation of biomaterial, special sterile containers with a lid and a spoon, which are sold in any pharmacy, are best suited. In the absence of such, you can use a small glass jar, having previously disinfected it. Collect a little feces from different parts of the stool so that the picture of the study is as objective as possible. In total, an amount approximately equal to 2-3 teaspoons is enough;

It is better to deliver the container with the sample to the laboratory immediately. However, storage of the material in the refrigerator for no more than 12 hours is acceptable. This is especially helpful with young children whose stools are unpredictable, or people who are used to having a bowel movement before bed.

Research methods: pros and cons

Currently, four main methods for determining occult blood in stools are used:

Gregersen reaction (benzidine test);

Weber reaction (guaiac test);

Let's look at the essence of these methods, their advantages and disadvantages. Looking ahead, we note that in Russia the most commonly used benzidine test and immunochemical analysis, but are they the most accurate?

Gregersen reaction (benzidine test)

The benzidine test is a simple and quick laboratory test that allows you to detect blood not only in the feces, but also, for example, in urine, vomit and any other body fluid of the patient. This is possible due to the oxidation of benzidine (paradiaminodiphenyl) with hydrogen peroxide or barium in the presence of hemoglobin. The benzidine test has several variations, the most commonly used of them was proposed by the doctor M. Gregersen, and therefore bears his name.

The essence of the method is as follows: take 0.025 g of benzidine, add 0.1 g of barium peroxide and 5 ml of 50% acetic acid solution to it, shake everything until completely dissolved, put a few drops of the composition on a glass slide, on which the test feces are smeared with a thin layer, and watch the reaction. If there is occult blood, a bright blue-green coloration occurs. There is an alternative - prepare a saturated solution of benzidine in acetic acid and mix with a 3% solution of hydrogen peroxide in equal parts. The result will look about the same, and the cost of the study will change little.

Pros:

Very high sensitivity - 1:100,000;

The speed of obtaining the result - almost instantly;

Availability in any laboratory;

Low price.

Minuses:

The need for careful preparation for the delivery of a fecal occult blood test using the Gregersen method, since the benzidine test gives a positive reaction to animal hemoglobin from food.

Weber reaction (guaiac test)

In addition to the two voiced, this diagnostic method has several more names: the Van Deen or Almen-Van Deen test, the hemoccult test. Curiously, the reaction using guaiac resin is the first method in world medical practice for detecting occult blood in feces and other human biological fluids. Dr. Van Deen proposed it in 1864, and it is still actively used in many countries.

The essence of the guaiac test is as follows: they take 3-5 g of the test feces, dissolve it in acetic acid, and an ethereal extract is released, hydrogen peroxide and tincture of guaiac resin are added to it, and then the color change of the reagents in the test tube is observed. If the composition turns blue, then the test result for occult blood in the feces is positive. The test is repeated a total of six times: two samples are studied from biomaterials taken consecutively within three days.

Pros:

Efficiency.

Affordable price.

Minuses:

Low sensitivity - the reaction will be positive only in case of blood loss in the amount of 30 ml or more, colorectal cancer is found in a third of cases, benign intestinal tumors - only in 15% of cases;

Strict dietary requirements before testing feces for occult blood - guaiac test is sensitive not only to human hemoglobin heme peroxidase, but also to peroxidases of other hemes contained in food.

This analysis is otherwise called an immunological or immunochromatographic test. The technique is based on the reaction that occurs when specific antibodies interact with human blood hemoglobin. Errors are excluded because the antibodies do not react to animal hemoglobin or the iron found in some plant foods. Immunochemical analysis of feces for occult blood appeared in the arsenal of physicians relatively recently and has already firmly established itself there.

The essence of the technique is as follows: a sample of the studied feces is applied to a test strip or placed in a tablet window with reagents - monoclonal antibodies. If human hemoglobin is present in the biomaterial, it binds to antibodies, and a bright pink or purple band appears in the control area. The second band appears in any case - it is an indicator of the quality of the device. Taking a fecal occult blood test using this method is very similar to taking a pregnancy test - everything is very simple, fast and understandable.

In a pharmacy, you can purchase "ImmunoCHROME-GEM-Express" or any other similar device for self-diagnosis of hidden gastrointestinal bleeding at home, however, to obtain a reliable result, it is recommended to conduct an analysis at least three times with intervals of several days.

Pros:

Speed ​​and convenience;

No need for preliminary preparation and diet;

High accuracy - determines the early stages of colorectal cancer in 97% of cases.

Minuses:

Relatively high cost;

Availability not in every laboratory;

The objectivity of the results of the analysis of feces for occult blood only in the case of bleeding in the lower parts of the digestive tract. Aggressive enzymes that act on hemoglobin in the stomach and small intestine make it unsuitable for reaction with monoclonal antibodies.

To complete the picture, it should be mentioned that occult blood can be detected in feces during a chemical reaction using destructive reagents. Nitrogen-containing pigments, porphyrins, contained in hemoglobin molecules and released outside when they die, have an ultra-high light absorption coefficient - about 10 to the 6th degree. Their bright fluorescent glow is recorded by the laboratory assistant in the event that there is occult blood in the studied stool sample. However, in Russia this diagnostic method is not very popular, especially in comparison with the benzidine test.

Pros:

Efficiency;

Affordable price;

Relatively high accuracy - about 80%.

Minuses:

The need to follow a diet, since porphyrins are present in any hemoglobin, including in an animal.

Deciphering the results of an occult blood test

Depending on how the test was carried out and what the internal regulations of the laboratory are, you will receive an answer in 1-6 days. From the description of the methods for conducting this study, it can be seen that its results cannot be expressed in an exact digital equivalent: in the benzidine and guaiac samples, the reagent is either stained or not - only the speed and intensity of the color differ. As for the enzyme-linked immunosorbent and fluorescent test, everything is also clear here: the second strip either appears or not, and the glow is either there or not.

For example, consider the decoding of the results of the analysis of feces for occult blood according to the Gregersen method (benzidine test):

Important: even a weak reaction usually alarms the doctor and prompts him to repeat the test or add additional diagnostic methods to it, since the presence of latent blood in the feces is a sign of serious trouble.

Let us now consider why the results of the study may turn out to be biased:

False negative fecal occult blood test result- this is almost always a consequence of a violation of the technology of conducting a sample or poor quality reagents. It may also be that the patient provided little biomaterial or was too lazy to collect it from different fragments of feces. In addition, in some diseases of the gastrointestinal tract, for example, with polyposis of the large intestine, neoplasms bleed not constantly, but episodically. Therefore, the study is recommended to be repeated several times, especially if there are serious reasons to suspect the disease;

False positive occult blood test result- this, in most cases, is a consequence of neglecting the rules of preparation. Either the patient did not follow the diet prescribed by the doctor, or took any medications that distorted the picture of the study, or allowed an injury that led to blood entering the gastrointestinal tract. In infants, a positive fecal occult blood test result can be false if the nipples of a nursing mother are cracked and bleeding - then the baby swallows blood during feeding, and it ends up in his stool. Moreover, this problem cannot be solved by pumping, the blood in this case can also get into breast milk. It is better to transfer the baby to an artificial mixture for three days in order to be sure of the objectivity of the test.

Positive result - what to do?

Anxious patients are primarily concerned with the question: what does a positive fecal occult blood test result mean? First of all, this is definitely not a reason to panic. We have already discussed the rather high probability of errors, especially when preconditioning rules are violated. It is imperative to repeat the study at least three times before drawing final conclusions.

Secondly, even if a positive result turned out to be reliable, it most likely signals the most common diagnoses:

An occult blood test is an opportunity to identify diseases that cannot be seen with simple tests. The study reveals a variety of serious illness which are characterized by damage to the alimentary tract. Including various cancerous tumors, Crohn's disease, ulcerative colitis and others.

An occult blood test is prescribed by the attending physician in case of suspicion of bleeding in the gastrointestinal tract. This problem can become a sign of many diseases, including cancer.

Oncological problems with the large intestine, already at the initial stage of manifestation, can cause constant, mild bleeding. They appear due to the fact that neoplasms consisting of cancer cells often bleed and the blood enters the large intestine directly.

In this case, blood in the stool can be detected using a routine analysis. But in rare cases, blood can only be detected during occult blood test.

A positive test result may be due to the following diseases:

• helminthiasis (infection with large helminths that can injure the intestinal wall);
• polyposis (overgrowth of polyps in the intestines);
• ulcer (inflamed intestinal microtrauma caused by bacteria);
• inflammatory processes on the gastric mucosa and in the intestines;
• hemorrhoids and hemorrhagic diathesis;
• typhoid fever;
• pathology of the stomach;
• Crohn's disease;
• neoplasms in the large intestine;
• pathology of the duodenum;
• cancerous tumors.

Decryption

Occult blood can only be detected by microscopic or hemoglobin testing ( guaiac test). It is allowed to use tests based on monoclonal antibodies that react to the presence of hemoglobin.

The high sensitivity of such tests allows them to be considered much better than conventional express methods.

It should be borne in mind that in some cases a completely healthy person can have a positive reaction, so only specialists can accurately determine the violation.

Fine, test for occult blood must be negative.

If the reaction is positive, there is a suspicion of chronic pathologies associated with the gastrointestinal tract. Usually this is damage to the mucous membrane.

In this case, blood can penetrate into the lumen of the large or small intestine, the stomach. At the same time, such a violation can be detected only with the help of an occult blood test.

Also, the reasons for a positive reaction can be:

• colitis;
• duodenal ulcer;
• nonspecific ulcerative colitis.

But a false positive result is manifested if the blood enters the stomach from the oral cavity, when a person suffers from hemorrhoidal bleeding, hematuria, helminthic invasion and others. Also, the reasons may be in strong stress during defecation and inaccurate delivery of feces for analysis during menstruation.

What to do if the analysis is positive?

In the event that the analysis is positive, it is necessary to undergo a diagnosis. Initially, this should be a colonoscopy. This diagnosis allows you to see the exact location of the gaps in the lower intestine.

If necessary, you can take a biopsy, after which more accurate information will be obtained about the cause of occult blood in the feces.

If the cause of the appearance of this pathology was the development of a tumor, in the future it will be necessary to consult an oncologist, as well as conduct magnetic resonance imaging.

Treatment

Treatment after a positive test result is detected, should only be discussed with a doctor.

In no case should you self-prescribe medications or use traditional medicine, as they can cause even more harm to the body.

Positive analysis in infants and children under three years of age

Any change in the concentration and color of the stool in the baby causes anxiety in parents. But with a single change of chair, you should not worry. But if the scarlet admixture in the feces appears regularly, it is necessary to consult a doctor and take an analysis for occult blood in the feces.

A fairly common cause of blood in the stool is baby intolerance to cow's milk. Problems can arise even if the milk is consumed by the mother of the child, who continues to breastfeed. Problems can also begin if the mother eats butter, sour cream, cheeses and other dairy products.

If the child is bottle-fed, it is necessary to carefully select a formula that does not contain cow's milk protein.

If the baby has a positive test for occult blood in the feces, the problem may be in inflammatory bowel diseases:

• dysbacteriosis;
• amoebiasis;
• colitis;
• dysentery;
• balantidiasis.

An accurate diagnosis can only be made based on examination and coprogram.

Another cause of occult blood in the feces can be an infection caused by the introduction of adult products into the baby's food.

Such a problem may also be accompanied by vomiting, diarrhea, abdominal pain, high fever.

In older children (from two years old), a positive reaction to occult blood in the feces can be observed in case of problems in the large intestine - juvenile polyps. Such formations do not cause discomfort to the child and are not dangerous to his health. If desired or necessary, they can be removed.

In order to determine the state of the human body, you need to undergo an examination and pass some materials to the laboratory for research. There are a large number of varieties of tests, one of them is feces for occult blood. Preparation takes several days.

Collection of feces for occult blood: indications

The analysis is needed in order to determine whether there is damage to the organs of the gastrointestinal tract. If the integrity of the mucous membrane of at least one organ is broken, this will be seen from the results.

Reasons for analysis may include:

In addition, feces for occult blood are taken if there is a suspicion of an oncological disease or a benign neoplasm.

You can take a referral for analysis from a surgeon, therapist, oncologist or gastroenterologist.

What do you need to know about the study?

At the present stage, everyone who is being tested for occult blood needs to have at least general information about this.

The fresher the sample, the more accurate the results will be.

Before taking the samples, you need a simple preparation for a few days.

The daily amount of dense excrement is approximately 200 grams. Significantly more comes out with pathological processes of the gastrointestinal tract, less - with malnutrition, the use of protein foods, and problems with defecation.

By the form, you can understand whether there are deviations in the work of the intestines. In a healthy person, the stool has a sausage-shaped form of medium density, brown. When disturbed, the feces can be very dense or liquid, lumps or in the form of a ribbon. In severe pathologies, not only the appearance changes, but also the composition, smell, various impurities appear.

In normal feces, there may be particles of undigested food - the norm is the peel of fruits or vegetables, cartilage or tendons.

If mucus or blood is visible to the naked eye, this indicates a disease of the colon.

Almost all patients know how the medical staff should behave. However, few people remember that there are also general recommendations for patients regarding the delivery of any analysis, including feces. They are as follows.

Feces are collected after a natural bowel movement. Do not use enemas or laxatives. It is not recommended to use it a few hours before collecting the sample, and special preparations for another 3-4 days. If you violate this rule, the analysis will not be accurate. However, this applies only when feces are donated for occult blood.

The accuracy of the results depends on the freshness of the material. The ideal option is if the sample reaches the laboratory within 3-6.5 hours after its collection. This rule is not always easy to follow, however, some microorganisms live outside for only a few hours. Therefore, getting a complete picture over time becomes more and more difficult. It is desirable to hand over the analysis till 10 o'clock.

3-4 days before sampling, special preparation is needed - diet. You can not eat a lot and those foods that cause discomfort in the stomach and intestines. Avoid foods that stain feces, such as beets, greens, and certain fruits.

If possible, do not take pharmaceutical preparations for a week before sampling. The exception is those that are taken regularly for chronic diseases. This is due to the fact that some drugs stain the feces in a different color or change the composition of the microflora. In addition, do not conduct additional bowel examinations using special enemas, such as barium. It discolors feces and changes their structure.

Collect the sample in a special jar-container with a spoon, you need to purchase it in advance. To make an accurate analysis, a few grams of the material is enough.

The last rule concerns women. During menstruation, sampling is not recommended, as blood can get into the excrement and spoil the results.

Diet before fecal occult blood test

A few days before sampling, a special diet is prescribed, which must be followed in order for the analysis to be correct the first time.

During this period, you can not eat:

Sample menu for one day:

• Bread and butter, milk soup, a few pears or peaches, canned in winter;
• Mashed potatoes, 2 boiled eggs, milk jelly;
• Yogurt without dye;
• A glass of kefir or fruit.

The amount of food taken at one time should not exceed 300-400 grams. The same set of products with some correction and variations should be eaten for another 2 days.

Feces for occult blood: decoding

Ready analysis, interpretation, is called a coprogram. First of all, the presence of blood, even in the form of individual cells, is not characteristic of feces. Therefore, a microscopic examination is carried out to find out if red blood cells are present in the excrement?

They can be there for several reasons: damage to the stomach and small intestine or lower part, that is, the rectum, colon and anus. If the bleeding is heavy, the discharge is already noticeable - the feces will be black, in case of minor damage, it is difficult to determine anything without special studies.

Damage to the lower digestive system is noticeable due to the presence of bright red impurities. Since some products and drugs can have a similar effect, you need to undergo a diagnosis, that is, donate feces.

This analysis will show if there are problems in the upper part of the food system, in the case of the presence of red blood cells in the material provided for the study. There are no special norms for this, even the smallest content of blood particles in the feces is enough.

If the gums or nasal mucosa bleed, the analysis will be positive. Therefore, careful preparation for the procedure is needed, and it is not recommended to brush your teeth the day before and try to avoid various injuries.