A stool test for occult blood is slightly positive. Analysis of feces for occult blood: preparation algorithm, interpretation and cost

Stool examination is an integral part of suspected diseases. gastrointestinal tract. Bleeding from various parts of the gastrointestinal tract ranks 5th among acute diseases digestive organs and are an important problem in clinical diagnosis. Bleeding can complicate the course of more than 100 diseases of various etiologies and, if not diagnosed in time, lead to death in 29% of cases.

Bleeding from the gastrointestinal tract can have varying intensity. Hidden bleeding, that is, bleeding of small volumes that does not lead to a change in the color of stool and does not cause alarming symptoms in the patient, represents the greatest difficulty in diagnosis.

The most common cause of the appearance of such blood in the stool is tumor diseases of the intestine, which initial stages Dont Have clinical symptoms. It is for the diagnosis of hidden bleeding that stool examination is used. occult blood. Currently, this is a screening method for determining tumor lesions of the gastrointestinal tract.

Indications for a stool occult blood test

The indications for testing stool for occult blood are quite wide. This method is used for screening diagnostics of intestinal tumor diseases in the middle age group. If you suspect tumor, inflammatory and other diseases of the gastrointestinal tract. For chronic anemia of unknown etiology. Thus, we can highlight the main goals of this study: detection of intestinal bleeding, early detection of colon cancer.

Preparing for analysis

Currently there are various methods determination of occult blood in feces, some of them do not require special preparation.

General recommendations for preparation before testing for fecal occult blood are used to minimize false-positive results in patients. 48-72 hours before the test, it is recommended to exclude meat products, fish, fruits, vegetables (cucumbers, horseradish, cauliflower), 7 days before the study you should stop taking medicines: ascorbic acid, iron preparations, magnesium, acetylsalicylic acid, non-steroidal anti-inflammatory drugs.

If the patient’s gums are bleeding, it is necessary to advise him not to brush his teeth 2-3 days before the examination and recommend rinsing his mouth with a 3% solution of baking soda.

Feces should be collected after three consecutive bowel movements, the material for research is collected by the patient independently, the material is taken from different areas.

Submission of analysis

Submission of material for research is usually done in the morning. It is advisable that no more than 8-12 hours pass from the moment of defecation to the study; the biomaterial should be stored before the study in a special container (preferably glass) at a temperature of 3-5ºC. You can take the test for research in a special plastic container.

How do they look for occult blood, how long does the analysis itself take?

Normally, stool contains a small amount of blood (2-2.5 ml/day), therefore, using various chemical tests, only amounts exceeding this can be detected.

When blood enters the intestinal lumen, it undergoes breakdown under the influence of digestive enzymes.

To detect occult blood in stool, most clinics use benzidine or guaiac test. Reactions to detect occult blood are based on the property of the blood pigment hemoglobin, which is found in red blood cells, to accelerate oxidative processes. An easily oxidized substance (benzidine, guaiac) changes color when oxidized. Based on the speed of staining and its intensity, weakly positive (+), positive (++ and +++) and strongly positive (++++) reactions are distinguished. The most common test is the guaiac test.

Quantitative test "Hemoquant"(based on fluorescent detection of porphyrins in feces) has twice the sensitivity compared to the guaiac reaction, but may be influenced by eating meat and taking acetylsalicylic acid for 4 days before analysis. Normally, the content of porphyrins in feces is less than 2 mg/g of feces; 2-4 mg/g - border zone; above 4 mg/g - pathology.

IN last years a completely new method for diagnosing bleeding from the gastrointestinal tract has been developed - immunochemical tests(for example, Hemoselect kits), which use specific antibodies to human hemoglobin. They make it possible to detect only human chemoglobin in stool, so when using them there is no need for dietary restrictions or medication intake.

What does a stool occult blood test show?

Negative result indicates the absence of intestinal bleeding. A positive stool reaction to occult blood is possible in the following diseases:

1) Diseases of the esophagus: peptic ulcers and erosions; cancer ; varicose veins of the esophagus; Mallory-Weiss syndrome.
2) Diseases of the stomach and duodenum: peptic ulcer; stomach cancer ; symptomatic gastroduodenal ulcers; gastroduodenal erosions.
3) Intestinal diseases: bacterial and protozoal colitis; tumors; ulcerative colitis ; Crohn's disease ; diverticular disease of the intestine or esophagus; infestations by helminths that injure the intestinal wall; intestinal tuberculosis; Meckel's diverticulum ulcer; hemorrhoids, anal fissure; polyps.
4) Blood diseases: coagulopathies; thrombocytopathy; hemorrhagic vasculitis; Rendu-Osler disease.

Also, it is worth noting the reasons for a positive result for occult blood in the absence of a pathological process: when blood enters the digestive tract from the oral cavity and larynx, with cracked lips, when blood is accidentally sucked out of the oral cavity and when it flows in cases of nosebleeds; getting into the stool of menstrual blood.

What to do if the test is positive

If the test result is positive, you need to consult a doctor for further examination to identify the cause.

At the first stage, the segment of the gastrointestinal tract in which the bleeding occurred is determined. Next, the immediate cause of the bleeding is identified.

To diagnose the source and cause of bleeding, various research methods can be used. Pathological processes in the esophagus, stomach and duodenum, esophagofibroduodenoscopy helps to detect it in approximately 93% of cases; if necessary, a targeted biopsy is performed.

X-ray examination of the upper gastrointestinal tract can also help in diagnosis. Diseases small intestine, accompanied by bleeding, are rare and are usually diagnosed after excluding other causes of blood loss using an X-ray examination of the intestine, radiocapsule endoscopy, diagnostic laparoscopy, and, if necessary, laparotomy.

Diseases of the large intestine as a source of bleeding can be detected by: examining the perianal area; digital examination of the rectum; sigmoidoscopy; X-ray irrigoscopy or colonofibroscopy with targeted biopsy; laparoscopy or laparotomy.

Meckel's diverticulum can be detected using selective angiography and intestinal scintigraphy with technetium 99, which accumulates in the diverticulum.

Thus, the reasons for performing this study are quite serious, so you should not refuse or neglect this method if your doctor has prescribed this test for you. Examination of stool for occult blood is an absolutely safe, painless and highly informative method. It is also worth doing this study as a screening method for diagnosing intestinal tumor diseases after 35 years.

Doctor Chuguntseva M.A.

Blood during bowel movements may indicate a serious illness, ranging from anal fissure to malignant neoplasm in the digestive organs.

However, in the early stages, the pathology often develops without obvious symptoms, and hidden bleeding can be difficult to notice.

Fecal occult blood test detects the smallest blood impurities and allows you to diagnose diseases in initial phases, which is extreme if you suspect cancer.

In what cases is it prescribed?

A stool occult blood test is prescribed for the following symptoms:

• Stomach ache;
• Dyspeptic symptoms (heartburn, bloating, nausea) for a long time;
• Frequent diarrhea, constantly thin stool;
• Other digestive disorders;
• Sudden weight loss for no apparent reason;
• Clinical stool analysis does not show the presence of bleeding.

Presence of occult blood be sure to check if you suspect inflammation of the gastrointestinal tract, peptic ulcer, neoplasms.

Indications for this test quite serious, and if the doctor suggests doing a stool test, do not ignore his recommendations. Unlike many other methods of examining the gastrointestinal tract, the test is completely safe and painless.

Research methods

Modern laboratories use 2 main analysis methods:

1. Gregersen reaction, as a chemical stool occult blood test is called, is used to detect bleeding in all parts of the gastrointestinal tract. The test is sensitive to hemoglobin of both humans and animals, so special preparation and a meat-free diet are required before taking it.
2. Analysis of feces for occult blood using the immunochemical method prescribed for diagnosing pathologies of the lower part of the digestive tract. The test only tests human hemoglobin, so patients do not need to limit their diets to meat and iron-rich foods. Testing feces for occult blood without a diet is more convenient and is actively used as a screening test for.

Immunochemical analysis is considered more modern and sensitive, but it is not informative regarding bleeding in the esophagus and stomach.

The choice of method is made by the doctor, depending on the patient’s complaints. Before going to the laboratory, consult a specialist!

How to prepare?

Patient preparation depends on the chosen research technique.

Taking a stool occult blood test using the immunochemical method does not require changes in diet.

2 weeks before it you should refuse:

• From drugs that increase the risk of bleeding (aspirin, ibuprofen).
• From laxatives.
• From procedures that can damage the mucous membranes of the gastrointestinal tract (enemas, colonoscopy, etc.).

Preparation for analysis using chemical samples includes a special diet. The Gregersen reaction can give a false result for digested hemoglobin and myoglobin in meat products, and for some vitamins and nutrients.

When testing for fecal blood, the diet excludes:

• Meat;
• Liver and other offal;
• Fish;
• Apples;
• Beetroot;
• Spinach;
• Paprika;
• Tomatoes;
• Other foods rich in iron.

The diet should start 3 – 4 days before the test, in addition, for this period you should:

• Avoid taking medications, foods, and drinks that can stain stool and affect intestinal motility;
• Avoid enzymes;
• Do not use rectal suppositories;
• Postpone x-ray examination of the gastrointestinal tract;
• Replace brushing with hygienic rinsing to prevent damage to the gums and blood from entering the mouth. oral cavity into the esophagus;
• Women do not perform a stool occult blood test during menstruation and 3 days before and after it..

How to assemble?

Proper preparation and delivery of the analysis affect the reliability of its results.

In no case should foreign impurities enter the material being tested.: water, urine, genital secretions, radiopaque compounds, suppository components, etc.

How to prepare for stool collection:

1. Purchase a sterile container. It is a container with a screw cap and a spoon. Containers are sold in pharmacies and laboratories.
2. Disinfect a vessel, potty, or other container suitable for defecation. Wash with soap, rinse several times with clean water, and pour over boiling water. You cannot collect feces from the toilet.

How to collect analysis:

• Only natural feces are suitable for research, without laxatives or enemas.
• You should defecate in a prepared container, avoiding urine.
• Use a special spoon to take the feces and transfer the material into a container.
• Close the lid.
• Attach a stool occult blood test form issued by the laboratory or prescribed by a doctor to the container.

The amount of feces for analysis is no less than a teaspoon and no more than 1/3 of the volume of the container. It is advisable to take not one, but several fragments of stool, so that the detection of hidden blood is as effective as possible.

How to submit?

Prepared feces cannot be stored; only fresh material that has not been frozen or preserved is suitable for analysis.

The best option for handing over a container, if it is not possible to deliver it to the laboratory immediately, is to put it in the refrigerator at a temperature of + 2 - 8°C, and transport it in a thermos with an ice cube. Maximum storage time is no more than 3 hours.

The result of a stool occult blood test is prepared within a few days. Typically, the study period is 3–6 days, depending on how long the analysis is done in a particular laboratory.

Analysis results

Norm of blood excretion in feces healthy person– up to 2 mg of hemoglobin per 1 g of material. A positive result means that occult blood has been detected in the feces, but its source must be further identified.

The intensity of the reaction is expressed by the number of “pluses”: from one – weakly positive, to four.

The Gregersen occult blood test may show:

• Erosive gastroduodenitis;
• Exacerbation of ulcers;
• Tumor in the stomach, intestines;
• Diverticulum;
• Varicose veins of the esophagus;
• Haemorrhoids;
• Intestinal tuberculosis;
• Crohn's disease;
• Polyps;
• Nonspecific ulcerative colitis.

With the chemical research method, there may be other reasons for hidden blood in stool analysis that are not related to gastrointestinal diseases.

False positive result probable if diet is violated before stool donation, in the presence of bleeding in the nasopharynx, helminthic infestation, blood diseases, menstruation. A fecal occult blood test in infants can be positive in cases of allergies, lactase deficiency, and constipation.

What does the immunochemical method show?: A result >50 ng/mL indicates hemorrhoids, polyps, colorectal carcinoma, ulcerative colitis, or Crohn's disease.

A physician should interpret laboratory results. If the test for occult blood in the stool is positive, additional tests should be performed. diagnostic measures to clarify the pathology.

Where to do it?

Having received a referral for testing, the patient himself has the right to choose where to donate feces for hidden blood: in a public clinic or a private laboratory (Invitro, Helix and others).

The price of the service is in the range of 350 – 700 rubles, depending on the technique used.

An immunochromatographic stool occult blood test has been developed for use at home. This is a quick and simple tablet test that detects human hemoglobin cells in feces.

How to do the analysis yourself:

• Purchase a test at the pharmacy to diagnose hemoglobin in human stool;
• Open the package;
• Collect feces with a special applicator into a container with a reagent;
• Place 2 drops of liquid onto the indicator tablet;
• Wait for the result.

By following the algorithm, you can quickly and with a high degree of reliability (up to 99.9%) detect the presence of bleeding in the gastrointestinal tract: two strips - test and control, which means the stool test for occult blood is positive and it is necessary to urgently contact a specialist.

A stool occult blood test detects even a small amount of blood, makes it possible to detect diseases in the primary stages, and this increases the likelihood of a favorable outcome. In the initial stages, the pathology is asymptomatic, and it is impossible to independently detect internal bleeding. Biological fluid in feces can indicate a dangerous disease - from hemorrhoids to malignant neoplasm.

• colorectal cancer;
• abnormal growth of tissue over the mucous membrane of the large intestine;
• ulcers, stomach erosions;
• diverticular disease of the colon;
• granulomatous enteritis;
• inflammatory processes that damage the inner lining of the intestine;
• haemorrhoids;
• nonspecific ulcerative colitis.

In young children, this may be due to individual sensitivity to cow's milk. If the baby is breastfeeding, then the mother's consumption of dairy products is to blame for the bleeding.

Indications for prescribing analysis

The study is a typical method for detecting a malignant tumor of the colon and rectum in the initial stages of development.

A positive test result may indicate the development of colorectal cancer

The doctor prescribes the donation of biomaterial if certain symptoms are present. which the patient addresses:

• abdominal pain, acid reflux, nausea, vomiting (follow this link to find out);
• systematically repeated false urge to defecate;
• regular constipation or diarrhea, fever, chills, lack of appetite, rapid weight loss;
• after detection of tumors in the gastrointestinal tract, diagnosis is necessary to exclude internal bleeding;
• helminths - a study is carried out to determine the degree of damage to the inner lining of the gastrointestinal tract (from this publication you will learn);
• previously discovered ulcers, Crohn's disease, infectious diseases caused by Mycobacterium tuberculosis.

Testing every 2 years is prescribed during preventive examinations after 50 years for timely diagnosis colorectal cancer. Indications for the test pose a health risk. If your doctor recommends a stool test, you should not take it lightly. The process of taking a stool occult blood test is absolutely safe and painless. The diagnostic price varies from 300 to 750 rubles.

Watch in the next video what the indications may be for prescribing a stool test for occult blood.

Types of occult blood tests

Laboratory testing allows you to find biological fluid in the intestines. The research is carried out in two ways:
1

Benzidine test (Gregersen method)

The method detects the presence of hemoglobin even in a small volume - which is both an advantage and a disadvantage of this type of study. Used to register colorectal bleeding.
2

Immunochemical method

The fecal occult blood immunochemical test focuses exclusively on human hemoglobin, so there is no need to follow a diet that excludes foods rich in iron-containing protein before the test.

The method is not able to detect colorectal bleeding in the stomach, esophagus and duodenum.

The immunochemical type is more reliable, it will detect 0.05 mg of iron-containing protein in 1 g of sample (with 0.2 biomaterial the test is positive). The choice of type of testing is made by the doctor and depends on the reason for issuing the referral for testing.

Preparing for analysis

To take the benzidine test, you should stop taking certain medications, in particular aspirin, for 3 days

The test result will be accurate if you follow the rules for preparing for the test. They are different for each method (in this publication you will read how to prepare for the test).

Preparation for stool occult blood test using the Gregersen reaction:

• Within 3 days before submitting the biomaterial, stop eating meat, liver and other foods that contain iron (chickpeas, lentils, cashews, apples, dark chocolate, etc.).
• For 3 days, do not take medications that contain iron, ascorbic acid, aspirin and non-hormonal drugs that have an anti-inflammatory effect. Discontinuation of medications should be discussed with your doctor.
• Women are prohibited from donating feces for diagnostics during menstruation, 3 days before and after.

How to take a stool occult blood test, which is performed using an immunochemical method:

• There is no need to adhere to a special diet before testing stool for occult blood..
• When taken regularly medicines increasing the risk of bleeding, it is important to consult your doctor about the procedure for conducting the study.
• The test is prohibited from being taken within 14 days after undergoing instrumental methods for diagnosing the digestive tract, which can lead to a violation of the anatomical integrity of the mucous membrane (these include colonoscopy, sigmoidoscopy and others).

Compliance with the rules is the key to obtaining a reliable result of the study of biomaterial.

How to properly collect feces

The material is collected from the vessel into a universal container using a special spatula attached to the lid of the container

The collection is carried out after spontaneous defecation (taking biomaterial after using an enema or laxatives is not allowed!).

The material is collected in a universal transport container. You can buy a container at pharmacies and laboratories.

The required sample volume is tsp. from 3 servings. It is forbidden to take areas contaminated with urine and discharge from the genitals. Material containing blood is not examined.

You can't take material out of the toilet. To do this, use a duck or a special vessel. In newborn babies, feces are collected from a cotton diaper immediately after defecation.

How to get tested

Having received a referral for a test, the patient independently decides where to go for the test: to the state medical institution or to a private laboratory.

Rules for storing and transporting feces: up to 12 hours at a temperature of 4-8 °C. The biomaterial must be delivered to the laboratory on the day of collection.

How much stool occult blood testing is done depends on the method chosen. The study using the immunochemical method takes about 14 days, and the Gregersen reaction - 4 days.

There is a test for rapid research using the immunochromatographic method. To implement this, a tablet has been developed that reacts to human hemoglobin cells in feces.

How to conduct express research yourself:

• buy a rapid diagnostic test at a pharmacy;
• open the package;
• collect feces with an applicator into a container with a reagent;
• Add 2 drops of liquid to the tablet with an indicator;
• wait for the results to appear.

The appearance of two stripes means that the diagnosis of the biomaterial for colorectal bleeding is positive; you should consult a doctor for further clarification of the circumstances. Correct use of the rapid test allows you to obtain a result with a reliability level of 99.9%.

Read in this article how to decipher a urine test for protein levels.

How to determine the presence of blood in stool

There are two types of stool occult blood tests: the immunochemical method and the benzidine test.

The Gregersen reaction is carried out as follows: 0.025 g of basic benzidine and 0.1 g of barium compound with oxygen are mixed, and 5 ml of 50% ethanoic acid is added before the test. The reagent is shaken until a homogeneous solution is obtained.

A thin layer of biomaterial is applied to the cover glass with a smear, then a few drops of the prepared reagent are added on top.

The color of the biomaterial in blue or green indicates the presence of biological fluid. This is due to the fact that when interacting with benzidine, the hemoglobin molecule is oxidized by hydrogen peroxide and changes color.

Analysis of feces for occult blood by the immunochemical method is based on the antigen-antibody adhesion reaction between the human iron-containing protein and anti-HbF antibodies present in the sample on latex microspheres. The adhesion and precipitation from a homogeneous suspension of antigen-bearing cells under the influence of specific substances is measured as an increase in absorbance of 570 nm, the size of which is directly dependent on the level of hemoglobin in the sample.

Decoding the results

Normally, the human body excretes blood with feces in the amount of 2 mg or less of iron-containing protein per 1 g of material. A positive result indicates the presence of internal blood in the biomaterial. The intensity of the reaction is marked with a “+” sign: weakly positive (“+”), positive (“++” or “+++”) and strongly positive (“++++”).

In a healthy person, the benzidine test result should be negative

In a healthy person, the result of a benzidine test test is negative. A negative indicator is not significant for establishing a diagnosis.

Positive means that the stool contains biological fluid in an amount greater than normal.

This is a sign of the presence of diseases such as: stomach ulcer, inflammation of the duodenum, ulcerative colitis, malignant tumor of the stomach, thrombophlebitis, varicose veins of the esophagus, stomatitis, periodontal disease, periodontitis, bleeding from the gums or nasopharynx.

If the result is positive, it is necessary to retest, since there is a possibility of an incorrect result due to deviation from the instructions for obtaining the biomaterial.

The standard result for stool occult blood analysis using the immunochemical method: 0-50 ng/ml.

A positive stool occult blood test indicates bleeding in the digestive tract. Based on the test results, it is impossible to judge in which part of the digestive tract it occurs and what the reason for this is. To obtain additional data, endoscopic diagnostics (sigmoidoscopy, colonoscopy) are required.

If a negative result is obtained, the presence of colorectal cancer cannot be completely ruled out. Only a specialist should interpret the stool occult blood test.

Causes of false positive and false negative results

In some cases, the result of a stool occult blood test is false positive. The reason for this may be poor preparation for collecting material. A false positive test may be due to bleeding from the gums and nose, causing the person to swallow a small amount of blood.

A false positive result may be the result of menstrual fluid in the stool, as well as adherence to a meat and fish diet.

False-negative indicators can occur if there is no free hemoglobin in the feces, but only undestroyed fresh red blood cells as a result of external bleeding (for example, from an anal fissure).

Taking stool samples 2-3 times is more informative. This will eliminate false positive and false negative indicators. If the repeated test shows the original result, then it is reliable.

conclusions

A diagnosis cannot be made based on what a stool occult blood test shows. A positive result means that the disease is progressing and, in combination with the signs and symptoms exhibited, allows a preliminary diagnosis to be made.

Content

Pathologies of the duodenum, stomach, and esophagus may be accompanied by internal bleeding. Stool analysis helps identify them at an early stage. The study detects occult blood, which often becomes a sign of cancer.

What is occult blood in stool

Traces of blood in excrement that are invisible to the human eye are called occult blood. They are discovered only when special analyzes to detect transferrin or hemoglobin. The study gives the most reliable results in identifying the following pathological conditions:

• ulcer of the duodenum, stomach;
• helminths in a child;
• tuberculosis of the intestine;
• blood diseases;
• varicose veins of the esophagus;
• Crohn's disease;
• erosive esophagitis;
• cirrhosis of the liver;
• Lynch syndrome;
• hemorrhagic diathesis;
• tumors;
• polyposis;
• inflammation of the tonsils, pharynx.

Stool analysis can detect colorectal cancer and intestinal tumors at an early stage. Positive test results are typical for the following pathologies:

• diverticula of the intestine, stomach;
• erosive gastroduodenitis;
• nonspecific ulcerative colitis;
• damage to the mucous membrane of the digestive organs.

When is an occult blood test prescribed?

Doctors prescribe a stool test for patients when signs of disease appear. digestive system. Indications for research are the following symptoms:

• abdominal pain of unknown etiology;
• false urge to defecate;
• causeless loss of body weight;
• diarrhea;
• constipation;
• hyperthermia;
• nausea;
• heartburn;
• vomit.

Methods for detecting occult blood in stool

If internal bleeding is suspected, doctors use different ways stool examinations. They are distinguished by sensitivity, efficiency, the need for preparation, and the identification of pathologies in various parts of the intestine. Diagnostic methods for occult blood, their advantages and disadvantages:

Benzidine test	instant results; high sensitivity; availability; low price	required: careful preparation; following a strict diet; correct collection of biomaterial
Immunochemical test	no dietary restrictions required; high accuracy, sensitivity; efficiency; lack of reaction to hemoglobin in foods, medications	not carried out everywhere; high price; objectivity only in case of blood loss in the lower intestines (enzymes of the small intestine and stomach interfere with the reaction)
Guaiac test	availability; efficiency	sensitivity only to large blood losses; high demands on diet; the test is performed 6 times

Benzidine test

This stool test to detect hidden blood loss has a second name - Gregersen's test. The main reagent is benzidine, to which acetic acid and barium peroxide are added to increase activity. The technique gives many false positive results - a reaction to nosebleeds, eating meat, drugs, bleeding gums.

Immunochemical test

Surgical research detects tumors in the colon at an early stage and reduces cancer mortality by 30%. Immunochemical analysis of feces for occult blood reacts only to human protein and does not require special preparation. It is characterized by high sensitivity and the following features:

Guaiac test

The sensitivity of the guaiac test depends on the hemoglobin concentration. If its content is more than 2 mg per gram of feces, the result is positive in 90% of cases. The test diagnoses bleeding in any part of the digestive system. The analysis has the following specifics:

Rules for preparing for research

To obtain an accurate test result, proper preparation is important. The process begins a week before the analysis and includes the following activities:

Time to study	What to do
	eliminate laxatives; don't use enemas	affect intestinal motility
	stop taking: preparations containing iron; non-steroidal anti-inflammatory drugs; Aspirin; vitamin C	change the color of stool
	don't have anal sex	possible damage to mucous membranes
	remove from diet: green onions; apples; spinach; broccoli; pepper; beets; tomatoes; garlic	include iron, pigments
	exclude fish, meat, offal (for guaiac or benzidine testing)
	Deadline for performing a stool test: x-ray studies; colonoscopy; sigmoidoscopy	contrast agent may distort the result; special devices often damage mucous membranes
	do not eat hard foods; her brushing her teeth	possible injury to the gums, blood getting into the stool

Features of preparing for the Gregersen test

To exclude errors in the results of this method, it is important to strictly follow the diet. Gregersen's reaction to occult blood is sensitive to iron, pigments from food. It is necessary to postpone research for a while under the following circumstances:

• presence of blood in the urine (hematuria);
• menstruation in women;
• hemorrhoids with bleeding;
• periodontal disease;
• indigestion (dyspepsia);
• ruptures, damage as a result of anal sex.

An important role is played by the correct collection of material for analysis. The following conditions must be met:

• carry out hygiene of the genitals and anus;
• collect feces in the morning, before breakfast;
• ingress of water and urine is unacceptable;
• you cannot take biomaterial from the toilet (you need to put an oilcloth on it);
• fragments must be from three places;
• put the stool in a special sterile container;
• deliver to the laboratory within two hours.

Interpretation of stool occult blood test

The doctor interprets the results of the study. The immunochemical test is considered the most accurate, but it is not performed in all laboratories. It takes 1-3 days to conduct and decipher the tests. Experts recommend that, upon receipt of positive and negative results, additional re-examination of stool for the presence of hidden bleeding and diagnosis using instrumental methods.

Negative result

If a small amount of blood enters the intestines, in a healthy person it is decomposed by enzymes. The norm is 0.2 mg of hemoglobin per gram of feces. A negative result confirms the absence of bleeding or dangerous diagnoses in the body, or requires repeated testing when the patient exhibits signs of pathologies.

Positive

If a patient is suspected of having hidden bleeding, a positive test result is possible. It often indicates an early stage of diseases associated with damage to the mucous membranes:

• colorectal cancer;
• peptic ulcer;
• intestinal tuberculosis;
• tumors of the digestive organs;
• helminthiasis;
• pathologies of the esophageal veins;
• hemorrhoids.

Positive reaction to occult blood in a child

When analyzing stool in children, signs of hidden bleeding are sometimes revealed. The reason for a positive reaction depends on age:

False positive and false negative results

Often, stool examinations for the presence of hidden blood loss give ambiguous results - false negative, false positive. In this case, repeated tests must be performed and additional diagnostics carried out. A false positive response is possible in the following cases:

• lack of preparation for the study;
• presence of nosebleeds;
• violation of the recommended diet;
• use of medications;
• bleeding gums.

The cause of a false negative result may be a violation of the analysis technology or low-quality reagents. If there is a suspicion of the development of pathologies, a repeat examination is required. A false negative result occurs in the following situations:

• limited amount of biomaterial provided for testing;
• uneven distribution of blood particles in the stool;
• the presence of tumors, polyps that bleed occasionally.

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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?

A fecal occult blood test can detect some serious pathologies in the early stages. For example, for many years in a row there may be minor bleeding in the human body that does not make itself felt. The patient has no pain or deterioration in health.

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

• rectum;
• stomach;
• spleen;
• intestines;
• liver.

Hidden blood in the stool 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:

• meat products;
• fish;
• liver;
• apples;
• cucumbers;
• green onions;
• some types of beans;
• spinach;
• Bell pepper;
• cauliflower.

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. It is worth refraining from lighting candles, as this may change chemical composition feces

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 what to bring the biomaterial to the laboratory in, purchase special containers. You don't have to fill it out completely. The third part is quite enough for the study.

Is any stool suitable for testing?

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

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 submit the biomaterial exactly according to the rules. This will help your doctor detect hidden diseases in a timely manner and begin treatment in the early stages.