Positive analysis for latent blood in feces

If symptoms occur before the appointment of a doctor should confirm the diagnosis with objective research. First of all, laboratory tests are performed, which are able to show a deviation from the norm.

The patient is assigned a common blood test, feces, urine. If a specialist has a suspicion that the pathology of the gastrointestinal tract is developing, leading to internal bleeding, then a test is appointed in order to detect it.

Why is an analysis done to detect occult blood in the feces of

? In the pathology of the mucosa of the esophagus, stomach, duodenum, the fecal masses become almost black or dark red due to the contact of blood with enzymes. If the integrity of the intestines is broken, the feces acquire a bright red color. With significant bleeding, the patient needs emergency medical care.

Bleeding is not always permanent, ulcers and inflammations bleed periodically. With a slight involvement of blood vessels in the pathological process, the shade of feces and their consistency does not change.

If a blood sample is not found during the coprogram, and the doctor suspects hidden bleeding, the patient must submit another analysis. The reaction to latent blood in feces is positive, and there is not necessarily bleeding, that is, the result is false positive.

When the

test is passed The occult blood test is recommended if the patient has the following symptoms:

• abdominal pain that is permanent or occurs intermittently;
• nausea and vomiting;
• heartburn;
• emptying by consistency is different from normal( mushy);
• false urge to defecate;
• frequent constipation;
• diarrhea;
• weight loss, lack of appetite;
• hyperthermia.

If the bleeding is not strong, then it's impossible to notice blood in feces without special reagents.

The study allows to confirm the diagnosis. It is also performed if the patient has been diagnosed with gastrointestinal disease using other diagnostic methods. The results will help the specialist to understand the degree of mucosal damage and determine the severity of the disease, and a second test will show how effective the prescribed therapy is.

How to take the

test The therapist, oncologist, surgeon, gastroenterologist can prescribe the test. Before the surrender, preliminary preparation is necessary. Doctors give the following recommendations.72 hours before the analysis, exclude from the menu iron-containing foods, as well as tomatoes and vegetables and fruits that have a green color. Do not eat meat or fish, because they have hemoglobin.

For a week, stop taking medications such as aspirin, laxatives, iron-containing tablets, non-steroidal anti-inflammatory drugs. If there is no possibility to suspend drug therapy, then the doctor should be informed about the medications taken.

Do not use products that alter the stool color. Collection of material should be carried out before the diagnostic manipulation in the digestive tract. It is not recommended to do an enema or take laxatives in order to speed up the receipt of a sample for analysis.

You can not collect a sample during menstruation. If X-ray diagnostics was performed, then the analysis can be taken only after 2-3 days.

If the examinee has periodontal disease, in which pronounced bleeding gums, then a day before the collection of stool is not advised to brush his teeth, since the blood trapped in the stomach is capable of giving a positive result.

Take the material from three different sides of the stool. An unreliable response is likely if water or urine enters the sample. In order to eliminate this it is recommended to lay the oilcloth on the toilet. The sample for inspection should be placed in a plastic container( it can be purchased at a pharmacy) and brought to the laboratory in the next 2-3 hours.

What does it mean if the result is positive?

Analysis for latent blood is positive if a pathology develops, in which a certain volume of blood enters the lumen of the stomach or intestine. That is, there is a disease, which is characterized by inflammation of the mucosa and its perforation.

A positive response indicates the development of the following pathologies:

• colorectal cancer;
• tumor;
• peptic ulcer;
• ulcerative colitis;
• intestinal tuberculosis;
• parasites that injure the intestinal mucosa;
• changes in the esophagus veins due to cirrhosis or thrombophlebitis of the splenic vein;
• erosive esophagitis;
• Rundu-Osler disease;
• hemorrhoids.

In some cases, the tumor manifests itself only by the release of a small volume of blood with feces

In young children, also can see blood in the stool. Quite often this is due to the child's intolerance to cow's milk. If the baby is breastfed, even the mother's milk, butter, sour cream can provoke bleeding.

Bleeding in a baby can be caused by dysbacteriosis, amebiasis, colitis, dysentery. One of the reasons for the presence of blood in the feces is the cracks in the anus, resulting from the passage of too hard feces. This happens if the child consumes little liquid.

Tumors in the colon are not strong, but are constantly bleeding from the time of formation. If the bleeding has become abundant, then it will also show up during the coprogram. An analysis of latent blood helps to see the symptoms of cancer in the early period, and this increases the chances of a favorable outcome of the disease. A positive test for latent blood will be due to bleeding from the nose or gums, pharynx.

How to detect the presence of blood in the stool

During the study, chemicals are used that, upon contact with the red blood cell under the influence of oxidation, change the color. Gregersen's method allows you to see even a small amount of hemoglobin. Benzidine stains the iron in blue.

With regard to the staining speed and its intensity, a weakly positive( +), positive( ++ or +++) and sharply positive( ++++) reaction are established. With the use of benzidine, blood loss of more than 15 ml / day can be established, which often gives false positive results.

Immunochemical analysis of stool is considered more accurate. It uses antibodies to human hemoglobin, so there is no need to follow a diet. The test is highly sensitive, it will detect 0.05 mg of hemoglobin per gram of feces( at 0.2 ml / g of feces is considered a positive test).

This method allows to detect tumor formations in the large intestine, but does not reveal bleeding from the esophagus or stomach. In 3% of cases, tests give a positive result in the absence of neoplasm in the large intestine.

Causes of false positive and false negative results of

Normally, there is no blood in the stool, so if there is no pathology that causes bleeding in the esophagus, stomach or intestines, the result of the analysis will be negative. In some circumstances, the analysis of feces for occult blood gives a false positive or false negative result.

Thus, often in the study, blood is not detected in the case of formation in the large intestine, so colonoscopy or flexible sigmoidoscopy is used to confirm colorectal cancer and polyps. False positive result can be obtained if there was no preparation for the study, if there is bleeding gums or the patient often has nosebleeds. Blood in the feces will be if a trauma is applied to the mucous membrane, for example, the patient cut the esophagus with a fish bone.

As a rule, a false positive test results if the patient ignores the doctor's recommendations and does not adhere to the

diet. More often the analysis is done for the presence of iron in stool, so even an apple eaten yesterday can stain the sample, which will be treated as the presence of blood. To exclude false-positive or false-negative results, it is recommended to perform the diagnosis three times( samples of three consecutive defecations) and follow all the recommendations for the preparation for research and collection of material.

If the analysis turned out to be uninformative, then the doctor will prescribe a hardware examination - a colonoscopy. It consists in examining the surface of the large intestine with an endoscope inserted through the anus.

This diagnosis will allow you to see the exact location of the lumen. To determine the condition of the mucosa of the esophagus or stomach, endoscopy is used, in which the flexible tube is inserted through the mouth. In order to rule out an erroneous result, it is recommended to take the analysis three times.

If the test results in a negative result, the doctor will not rule out a peptic ulcer or cancerous lesion of the digestive system. On the basis of the mere analysis of latent blood in the stool, it is impossible to diagnose, it only means that there is a pathology and, together with the clinical manifestations of the disease, allows establishing a preliminary diagnosis.