home Audience 6 How to properly test stool for occult blood. Preparing and performing a stool occult blood test

How to properly test stool for occult blood. Preparing and performing a stool occult blood test

Almost every person has at least once encountered the need to submit feces for analysis. However, to get true results, it is important to know how to do it correctly. One of the important laboratory tests is a fecal occult blood test.

Under what circumstances should it be carried out? What does it help determine? How to submit biomaterial for this study correctly? Let's figure it out.

Is it so important how you collect research materials?

It is important to understand that everything related to medical procedures must be systematic and orderly. This is why there are many rules and recommendations, for example, how to take certain medications and when is the best time to get tested.

The same is true for submitting stool for analysis. Routine microscopic examinations can provide an overall picture of your health. However, a fecal occult blood test is different from other laboratory tests.

Why get tested for occult blood?

It happens that nothing bothers a person, and there are no noticeable changes in the functioning of the digestive canal. Why take such an analysis anyway?

The analysis of feces for occult blood allows you to detect some serious pathologies in the early stages. For example, for many years in a row in the human body there may be slight bleeding that does not make itself felt. The patient has no pain or deterioration in health.

At the same time, such violations may indicate pathologies in such organs:

rectum;
stomach;
spleen;
intestines;
liver.

Hidden blood in the feces can be detected with hemorrhoids and thrombophlebitis of large internal veins. All this requires careful diagnosis and a sensitive approach on the part of the attending physician.

Reasons for unreliable analysis results

In some cases, the result of the analysis can be questioned. Most often this is due to the fact that the biomaterial for the study was not collected in accordance with the rules.

Blood may be detected in the following cases:

blood from menstrual fluid has entered the stool;
due to nosebleeds, it entered the esophagus and then into excrement;
From the cracked lips, blood fragments entered the body.

How to properly take tests for occult blood?

In order for the analysis result to be reliable, it is important to properly prepare for its delivery. This is not only about how to properly collect feces for research, but also what can be eaten for reliable results.

Preparing for the test two weeks in advance

If you have been receiving any antibiotic treatment, it should be stopped at least two weeks before the test. If this is not possible, the delivery of biomaterials should be postponed. Two weeks should pass between the last dose of antibiotics and the test.

Preparation measures one week before collecting biomaterial

You should stop taking the following medications for about a week:

vitamins;
aspirin;
any blood thinners;
preparations containing iron in any form;
non-steroidal anti-inflammatory drugs.

What is important to do three days before the procedure

During this period before the planned date, it is important to remove the following nutritional components from your diet:

Two days before analysis

In no case should biomaterial be taken for analysis less than two days after the X-ray examination. This may affect the results.

You should also not take activated carbon and bismuth. These drugs change the color of stool, making diagnosis difficult. You should refrain from using suppositories, as this may change the chemical composition of stool.

What women need to consider

It is not recommended to take such a test during menstruation. Blood from the vagina can penetrate the test material and distort the conclusions. If an occult blood test needs to be carried out urgently, then it is necessary to use a swab.

The importance of hygiene when collecting stool

Do not think that if the feces themselves contain a large number of bacteria, then hygiene is not so important. Small fragments of urine or chemical components from linens and clothing may interfere with the accuracy of the results.

First you need to urinate and wash well with warm water and soap. Then you need to defecate in a clean, dry container. You should not do this in the toilet, as there may be a large number of microbes there, the entry of which will distort the results of the analysis. A vessel or pot is suitable for these purposes. If these items are not in the house, you can use a clean bag or film, from which you can then take part of the sample.

Why should I bring a stool test?

Pharmacies have a solution to this problem. If you do not know how to bring the biomaterial to the laboratory, purchase special containers. You don't have to fill it out completely. For the study, the third part will suffice.

Is any feces suitable for research?

If the stool was obtained by taking laxatives or using an enema, it cannot be used for analysis. This shows that only the material that was obtained spontaneously is suitable for laboratory research.

It is best to use fresh feces. The ideal situation is when it is collected immediately before delivery to the laboratory. If this is evening feces, it is better to place it in the refrigerator, where the storage temperature will not exceed six degrees.

In order for the results of the analysis to be reliable, it is important to hand over the biomaterial exactly with the rules. This will help your doctor detect hidden diseases in a timely manner and start treatment at an early stage.

Gastrointestinal bleeding can be very tragic if it is not detected in a timely manner. In the case of pronounced red feces, doctors have no doubts about the presence of internal pathological processes, but some diseases are almost asymptomatic.

And only the smallest particles of blood in the feces are a sign of a disorder in the activity of the gastrointestinal tract. Conducting such a study requires compliance with a number of rules to exclude a false result.

Types of fecal occult blood tests

Damage to the digestive tract can be localized both in the upper and lower sections. If bleeding has opened in the stomach or duodenum, then the feces become dark red, and in the large intestine - bright red.

But not with every disorder such a chair appears. Often small ulcers and inflammations only occasionally bleed. There are cases of tumor development, the only symptom of which is only a small admixture of hemoglobin in the feces.

Laboratory research makes it possible to determine the presence of blood in the intestine. Analyzes are carried out in two ways:

Gregersen's method (benzidine test).
Immunochemical method.

Gregersen method shows the presence of hemoglobin even at very low concentrations. This is both an advantage and a disadvantage of analysis. In the presence of benzodine, the iron of the transport molecule is oxidized by hydrogen peroxide and turns blue.

The reaction occurs to hemoglobin, both human and foreign (contained in meat products). Therefore, to clarify the results, doctors often resort to the second method.

Immunochemical analysis kala is more accurate. It is based on the specific effect of antigens on antibodies characteristic of a particular person. The method is usually used for infectious diseases, but this does not affect the primary purpose of the study - determining blood in the stool.

And if it is additionally possible to establish the type of pathogenic microorganisms that provoked intestinal inflammation, the diagnostic measure can even be considered overfulfilled. The disadvantage of immunochemical analysis is its duration: only after 2 weeks do doctors make a diagnosis.

Fecal occult blood tests are not prescribed for no reason. Typically, the patient complains of abdominal pain or malaise. General indications for the test are as follows:

recurrent or constant abdominal pain;
regular nausea, vomiting, diarrhea, or heartburn;
chronic bowel disorder;
rapid loss of body weight for no apparent reason;
to confirm the diagnosis (for ulcers, gastritis, etc.).

Essentially, the purpose of the analysis is to detect damage to the walls of the intestines and stomach. And if the doctor insists on a detailed study of stool, the patient should not refuse.

The test is carried out without any internal interventions, so it will not hurt. However, the high sensitivity of the reagents requires special preparation of the patient.

Preparing for a stool occult blood test

Any research has an error. But in order for the results to be reliable, you must follow a diet before the analysis. First of all, you will have to give up meat and fish, because they contain hemoglobin.

The list of restrictions also includes iron-containing foods and all red foods (tomatoes, beets, etc.), which color the stool of even a healthy person. Diet is the key point, but doctors also name other requirements:

Discontinue medications 1 week before the test.
Ban on laxatives (including folk ones).
The day before the test, you should not brush your teeth (there is a risk of damaging your gums and distorting the results).
The analysis is carried out no earlier than 3 days after the x-ray examination.
Enemas are excluded (emptying should be natural).
Women get tested on days when they are not menstruating.

How to take feces correctly?

Not every person is able to observe such a prohibition as “you cannot eat.” Preparation for analysis requires mandatory fulfillment of this point, otherwise the result of the study will be very doubtful. But the process of collecting feces itself is also important:

It is necessary to prepare a container (sold at the pharmacy).
Feces are needed without any liquid (water, urine, etc.). To do this, it is allowed to lay oilcloth in the toilet.
After emptying, take 3 pieces of feces with a teaspoon.
Samples should be delivered to the laboratory within 3 hours.

A small amount of blood still enters the intestines - 1-2 ml. This is normal only if this volume is the daily limit.

Therefore, the analysis will always show the presence of blood in the stool, but can such a small amount be considered a sign of a disorder? No. No one has canceled natural processes, and doctors only take into account larger indicators.

False results

To obtain reliable results from a fecal occult blood test, preparation should not be ignored. And if you treat this process carelessly, the results are often false.

Moreover, both false negative and false positive. For example, doctors know for sure that a patient has polyps in the large intestine, but the analysis does not detect hemoglobin.

This is due to the fact that such neoplasms do not bleed constantly, but only periodically. But it would be foolish to deny the presence of polyps, especially if detected using an endoscope.

False positive result- also a common occurrence. If the patient neglected the rules for preparing and collecting stool, then it is quite possible that the study will show the presence of a high level of hemoglobin in the absence of internal bleeding. The analysis is usually carried out using the Gregersen method, which is sensitive specifically to iron.

By eating only 1 apple the day before taking stool, a person will simply distort the results. In addition, blood can enter the intestines due to trauma to the gums with a toothbrush.

Thus, non-compliance with the rules will give doctors a reason to perform a colonoscopy, the essence of which is to insert a probe through the anus. It’s better to undergo such an unpleasant procedure not because of your own negligence!

What does a positive result mean?

Still, the analysis may show the presence of high levels of hemoglobin in the stool. In this case, a colonoscopy is prescribed to clarify the diagnosis, because there are many causes of bleeding:

ulcer;
inflammation in any departments;
Crohn's disease;
hemorrhoids;
tuberculosis;
intestinal fissure;
benign or malignant tumor (polyps, cancer, cyst, etc.).

Often blood enters the intestines from the mouth or nose. However, vascular damage in easily accessible areas of the body is easily determined by the appropriate doctors (dentist and otolaryngologist).

Conclusion

Fecal occult blood testing is an important diagnostic tool. Sometimes only hemoglobin impurities indicate a pathological process in the intestines. And if violations are identified in a timely manner, then treatment will not be long in coming.

Every adult knows that if blood appears in the stool, this is a symptom of a disease that can be life-threatening. If such a pathology is detected, you should immediately consult a doctor. There are many diagnostic methods that detect hidden bleeding, one of which is stool analysis.

Why donate stool for occult blood?

Some diseases of the digestive system are asymptomatic in the first stages. However, blood particles can be detected in stool even at the beginning of the development of pathology through research. Their sizes are very small, so sometimes it is impossible to notice even under a microscope. At the slightest suspicion of the occurrence of certain diseases, doctors send the patient to take a stool test for occult blood. This test is carried out to detect bleeding from the following digestive organs:

liver;
intestines;
spleen;
stomach;
rectum.

How to properly prepare for the test

In order for the test for occult blood in the stool to be reliable, you should properly prepare for the test. First of all, on the eve of taking the material, you cannot do enemas, and the emptying process should be natural. Women during menstruation should refrain from testing. Before the procedure, you should not do any X-ray examinations for three to four days. On the eve of taking the test, it is forbidden to brush your teeth, because if the smallest blood particles enter the digestive tract from damaged gums, the results will be distorted.

Diet before stool occult blood test

Before the study, the patient is prescribed a three-day diet. Its essence is adding potatoes, butter, boiled eggs, dairy products, and cereals to the daily diet. In order for stool collection for occult blood to be effective, you must completely avoid the following products:

Refusal to take medications

It is necessary to refuse not only certain foods before taking a stool test for occult blood, but also the use of medications that contain iron. These are barium sulfate and bismuth. They are able to color stool in a color that is unnecessary for analysis. Also, you should not take any laxatives that affect intestinal motility and acetylsalicylic acid (aspirin).

How to collect a stool test

Examination of feces for occult blood involves the collection of material, but no special recommendations are required. The kit is collected in a sterile container. Stool should be collected in the morning and delivered to the laboratory or diagnostic center no later than 3 hours after bowel movement. The adequacy of the final results depends on how correctly the preparation for the analysis was carried out. How to properly test stool for occult blood:

urinate in the morning so that the stool does not contain urine impurities;
perform thorough hygiene of the genitals;
collect stool using a bedpan;
Using a spatula, carefully transfer the material into a clean container.

How much stool is needed for analysis?

Once preparations for a stool occult blood test have been made, collecting material is not difficult. This laboratory test requires a very small amount of feces. In pharmacies you can buy special plastic containers for these purposes. Such a jar should be filled no more than a third (10-12 ml). If it is not possible to deliver the material to the laboratory immediately, then you can store it for a day in the refrigerator or a cold place at a temperature of +6 °C and below.

Stool examination

A large-scale task is performed by blood tests in relation to hidden bleeding in different parts of the gastrointestinal tract. To carry out the test, a special chemical reagent is used that reacts to the minimum level of hemoglobin, including in animal meat eaten the day before. Heavy bleeding is visible to the naked eye, because the color of the bowel movement changes radically. Scarlet blood characterizes the pathology of the colon or rectum. A tarry, black consistency indicates a problem in the esophagus, stomach or small intestine.

In smaller-scale disorders of the gastrointestinal mucosa, the color and consistency of the collected material does not change. The presence of red blood cells is determined through microscopic examination. To diagnose bleeding, screening tests are used to help identify asymptomatic diseases. Most clinics use a sensitive guaiac test. Its reactions to detect pathology work due to the property of hemoglobin to accelerate all oxidative processes.

During the analysis, feces are applied to special filtered paper, then guaiac reagent, hydrogen peroxide, and acetic acid are applied. If the hemoglobin concentration is less than 2 mg per 1 mg of stool, then the test result is negative. When the reaction to occult blood in the stool is positive, even small metastatic and primary tumors can cause it, so the blood sensitivity test is widely used to detect colon cancer.

Decoding the analysis results

If after the examination the reaction of the collected material is negative for occult blood, this means that the state of the gastrointestinal tract is normal. When a positive result is determined, this means that the patient has chronic pathologies accompanied by damage to the mucous membrane. This test result may indicate colitis, colon polyp, duodenal or stomach ulcer. Due to hemorrhoidal bleeding, severe straining during bowel movements, helminthic infestation or blood from the mouth, false positive results may be detected.

In order for a stool occult blood test to show reliable results, appropriate preparation is required. The diagnosis and prescribed treatment depend on laboratory test results. Be sure to follow all your doctor’s recommendations regarding diet before collecting material.

Why do you need to get tested?

Already from the name of the laboratory test it is clear what a fecal occult blood test shows. Then the question arises: to whom and for what purposes is it prescribed? This analysis allows you to identify the presence of bleeding in the gastrointestinal tract, which, in turn, can occur for a variety of reasons. For example, according to these:

When there is heavy bleeding in the small intestine, the stool may turn black

If you have a history of one of these pathologies or its symptoms, stool tests for occult blood are indicated.

Preparation and delivery of analysis for adults

This analysis may be relevant for diagnosing various gastrointestinal diseases in both adults and children. For a transcript, see the article at the link.

When prescribing a stool test for occult blood, the doctor must tell you that special preparation is required before this laboratory test.

6 mandatory stages of preparation

A week before donating stool, stop taking medications, especially those that can affect gastrointestinal motility and the color of the material. This rule applies to all forms of medications, including oral (tablets, capsules, mixtures, infusions) and rectal (oils and suppositories).
Before taking the test, strict adherence to the diet will be required. Excluding certain foods from your diet (read which ones exactly) no less than 72 hours before the day of collection.
Defecation to collect material should only be spontaneous. No enemas or laxatives.
If any diagnostic examinations in the intestinal or stomach area have been prescribed, for example, sigmoidoscopy or endoscopy, it is necessary to reschedule them for another time (after collecting stool for analysis).
Although this rule contradicts hygienic standards, it is recommended that the night before donating feces not brush your teeth, but simply rinse your mouth. The fact is that even the most microscopic trauma to the gums can affect the results of the study.
During menstruation, women cannot have their stool tested for occult blood testing. We will have to reschedule the study for another day.

Kirimov P.A., proctologist, Health Plus Clinic, Moscow

After 40 years, the risk of cancer is known to increase.

Therefore, even if there are no health complaints, you should definitely come to your local physician for a referral for testing, or get examined in a private clinic.

Diet before tests

What should be the diet of the examined patient should be indicated separately. A special diet must be followed for at least 3 days before a stool test for occult blood.

Preparation and diet are key when taking the test.

Gregersen's method, according to which this analysis is carried out, is sensitive to iron, therefore, it is highly recommended to exclude all products containing this element.

Also, from the menu, you should remove food that can change the color of feces (blueberries, beets), promote constipation (rice, pastries from premium flour) or have a laxative effect (prunes, strawberries), causing flatulence (beans, soda).

So, you will need to exclude from your diet everything that can make the results of a fecal occult blood test false:

fish and some seafood;
meat and offal;
most vegetables (especially those that contain a lot of iron or have a laxative effect);
fresh apples;
berries, especially blueberries, strawberries and black currants.

What can you eat in this case? Include grain bread, butter, various cereals, chicken or quail eggs, and dairy products in your diet. Baked or boiled potatoes and some fruits are allowed in small quantities.

The container for the test material must be sterile

The container for transporting stool must be sterile. As a rule, this is a plastic or glass container with a tight-fitting lid. When using non-standard containers, you must boil them. described in detail in our article at the link.
After defecation, the material must be collected from 3-4 places in a single portion. A volume equal to half a teaspoon will be sufficient. Contact with feces of discharge from the genitourinary tract is unacceptable.
The sooner the material is delivered to the laboratory for research, the better. You can store it in a special container for a maximum of 12 hours, and the temperature should be from +4 to +8. If these conditions are not met, the result will be false.

How to properly prepare and take the test for your child

Parents are responsible not only for their own health, but also for the health of their children. You need to be attentive to the child’s well-being and mood, and do not ignore complaints of pain. Babies who cannot speak express their anxiety by crying loudly and incessantly. and if stool retention or diarrhea is observed, it is necessary to urgently take a stool test, including for occult blood.

Preparation

All recommendations for preparing for the analysis, including a special diet and drug withdrawal, are followed in children in the same way as in adults. Soda and various sweets with dyes are harmful to the gastrointestinal tract, and if you have not yet limited your child from consuming them, you definitely need to do this when preparing to donate stool.

Children in the first months of life usually eat only mother's milk. Therefore, in order for a fecal occult blood test in a baby to be reliable, a nursing mother must follow an appropriate diet and temporarily exclude medications. and read the articles at the link.

Polyakova V. I., pediatrician, children's polyclinic No. 1, Voronezh

Pathologies of the gastrointestinal tract are not always manifested by painful sensations, frequent bowel movements or delayed bowel movements.

After each baby's bowel movement, carefully examine the contents of the potty or diaper.

Collection, storage and transportation of material

General recommendations on how to collect a stool test for occult blood have already been described above. Urine in the container is unacceptable. To collect and deliver the material, it is not advisable to wear a diaper on the baby, as this may spoil the picture of the results. It is best to use a clean fabric oilcloth.

As for older children, then take feces after a bowel movement from the toilet is unacceptable. Ask the child to sit in the pot, which should first be doused with boiling water.

Children's feces should also be stored at a temperature of +4 to +8 and transported to the laboratory no later than 12 hours.

We decipher the results: norm and deviation, false positive and false negative

A stool occult blood test, like any other laboratory test, is always interpreted by the attending physician. You shouldn’t draw any conclusions on your own, much less self-medicate..

Norms and deviations in adults

The norm of the analysis of feces for occult blood is a negative result. But at the same time, it should be understood that 1-2 ml of blood still enters the intestines. This will also be considered a variant of the norm, but only in the case when stool is no more than once a day.

If a stool test for occult blood is negative, but other studies indicate the presence of gastrointestinal pathologies (for example, endoscopy clearly reveals polyps in the rectum), the result is considered false negative.

A positive result in most cases indicates the presence of pathologies of the gastrointestinal tract and liver. These can be polyps, ulcers, fissures, hemorrhoids and even a malignant tumor. Other methods of research will be required to clarify the diagnosis.

If the stool occult blood test is positive, you should not immediately panic. Before making a diagnosis, the doctor will prescribe a second examination. After all, it is quite possible that the results are false. Distortions can occur for the following reasons:

non-compliance with a special diet and other recommendations before the study;
bleeding in any part of the gastrointestinal tract is still present, but is temporary;
bleeding of the gums and nasal mucosa (you should definitely inform your doctor about this).

In addition, errors on the part of the laboratory are not ruled out. Such cases are rare, but they do happen.

Norms and deviations in children

In children's feces, as in adults, there should be no blood(more about). But it should be understood that during the first 3 months of life, the baby’s body adapts to extrauterine life, and the gastrointestinal tract still continues to form. Therefore, if a test showed hidden blood in the stool of a small child, minor deviations from the norm are allowed.

If hidden blood was detected in the stool, the doctor will give a referral for additional examination

The fact is that in an unformed intestine, the vessels are located very close to the surface and are easily deformed during defecation, and even with severe gas formation.

In this case, as well as with bleeding gums during teething, and with improper preparation for the analysis, a false positive result is possible.

But the situation cannot be left to chance either. First of all, you need to try to bring the baby's stool back to normal by reviewing. In case of gas formation, place the child on his tummy more often and give dill water. After these steps, be sure to retake the stool test, and if necessary, the pediatrician will prescribe a hardware examination.

Even in the absence of complaints, it is necessary to examine stool in older children at least once every six months for preventive purposes.

The presence of hidden blood in a child’s stool can often indicate damage to the liver and gastrointestinal tract by helminths. This disease occurs quite often in childhood, however, there are no obvious symptoms. Therefore, it is important to know.

In pediatrics, medical prescriptions should be treated with particular caution. Unpromising and aggressive treatment can harm the health of the child. It is necessary to strictly monitor all indicators, for example, to know what the blood sugar level is in children.

Conclusion

Unfortunately, in the modern world there are very few completely healthy people. This situation is further aggravated by the fact that many pathologies are hidden and are detected already in an advanced stage.

In order to detect the disease on time, regular diagnosis is necessary.: hardware and laboratory research. If the analysis is normal, but complaints persist, the studies should be repeated, as well as additional diagnostics, for example, ultrasound, endoscopy, sigmoidoscopy, FGDS. Remember, our health is in our hands.

It is tested for hidden blood, which is not detected by conventional microscopic examination. It helps to identify diseases in any part of the stomach or intestines, which are accompanied by a violation of the integrity of the mucous membrane. So, normally, in a healthy person, a stool test for occult blood should be negative, and if it is positive, then it is necessary to conduct a more detailed diagnosis of the health condition.

Indeed, as a result of this study, it is possible to identify small chronic bleedings that do not in any way affect a person’s well-being. Using this analysis, it is possible, for example, to diagnose rectal cancer at an asymptomatic stage: even in the absence of pain and other pronounced signs of the disease, it causes the appearance of slightly bleeding tumors. It can also be positive for occult blood in case of ulcers in the gastrointestinal tract, intestinal tuberculosis, cirrhosis of the liver, thrombophlebitis of the splenic vein, typhoid fever, hemorrhoids, and even when infected with a certain type of helminth.

Such a wide list of possible reasons that a stool test for occult blood is positive requires a more thorough examination of the patient to establish an accurate diagnosis. It should also be noted that a positive test result can also be a result of blood entering the esophagus during nosebleeds, cracked lips, or even when menstrual fluid is accidentally introduced into the test material.

Before testing for occult blood, you need to prepare. 3 days before the expected date of the study, the patient must exclude from the diet any meat, liver, fish, a number of fruits and vegetables, which contain large amounts of peroxidase, catalase and, of course, iron. These include cucumbers, cauliflower, horseradish, apples, spinach, white beans, green onions, and bell peppers. In addition, a week before the study, it is prohibited to take drugs C, acetylsalicylic acid (including tablets intended to thin the blood), and non-steroidal anti-inflammatory drugs. If the patient has undergone an X-ray examination of the intestines or stomach, the analysis is given no earlier than two days later. It is not done while taking antibiotics. After all, all these products, drugs and procedures can affect the results of the study.

If you don’t know what to wear for a stool test, go to the nearest pharmacy where you can buy a special container with a spoon, which is used to collect material for the study. You should not try to fill the entire jar; the laboratory needs no more than 1/3 of its volume. By the way, these same containers are purchased if you need to undergo a biochemical analysis to test for enterobiasis or helminth eggs. The material must be collected on the same day on which it will be submitted to the laboratory. If storage is necessary, it is better to leave the feces in a cold place, at a temperature no higher than 6 o C.