4007. Faecal occult blood test

A fecal occult blood test can detect altered hemoglobin in red blood cells even when red blood cells themselves are not detectable during microscopic examination of stool.

Detection of human hemoglobin in stool is a highly specific test for diagnosing lower gastrointestinal bleeding, as blood entering the intestinal lumen undergoes minimal degradation. Because fecal hemoglobin is an unstable analyte, false-negative results are possible when diagnosing bleeding in the small intestine and upper colon.

Concurrent fecal transferrin determination allows for the reliable detection of upper gastrointestinal bleeding. Detection of fecal transferrin is typical for bleeding from the upper and lower gastrointestinal tracts (in cases of significant mucosal damage).

This test detects the presence of occult blood in stool without specifying hemoglobin and transferrin levels.

Fecal occult blood testing (FOBT) using immunochromatographic methods is a qualitative determination of human hemoglobin and transferrin in stool, used to detect occult bleeding from various parts of the gastrointestinal tract. It is a modern technique that is significantly more sensitive than less specific chemical methods (guaiac and benzidine tests). It allows for the detection of altered hemoglobin in red blood cells even when red blood cells themselves are not detectable during microscopic examination of stool. Timely detection of occult bleeding is crucial for the diagnosis of a wide range of diseases: ulcerative lesions of the gastrointestinal (GI) mucosa, primary and metastatic GI tumors, diverticulitis, intestinal tuberculosis, ulcerative colitis, Crohn's disease, helminthic infestations with damage to the intestinal mucosa, necrotizing enterocolitis, and infectious intestinal lesions.

Detection of human hemoglobin in feces is a highly specific test for diagnosing lower gastrointestinal bleeding, as blood entering the intestinal lumen undergoes minimal degradation. Because fecal hemoglobin is an unstable analyte, false-negative results are possible when diagnosing bleeding in the small and upper colon. Concurrent determination of fecal transferrin allows for the reliable detection of upper gastrointestinal bleeding. Detection of fecal transferrin is typical for bleeding from the upper and lower gastrointestinal tracts (in cases of significant mucosal damage).

The test does not cross-react with hemoglobin and transferrin of animal origin, so the patient does not need to eliminate meat from the diet before the test.

The test detects the presence of occult blood in the feces without specifying hemoglobin and transferrin levels.

When?

• For long-term gastrointestinal symptoms, such as changes in bowel habits, abdominal discomfort, or chronic fatigue without an established cause.
• After age 40 – as part of colorectal cancer screening, even without symptoms.
• For unexplained anemia (especially iron deficiency).
• For follow-up care of patients with colorectal polyps or chronic bowel disease.
• Before colonoscopy as a non-invasive initial screening method.

Who should screen?

• For people over 40 – annual screening (especially men).
• For patients with a family history of colorectal cancer or polyposis.
• For individuals with chronic inflammatory bowel disease (Crohn's disease, inflammatory bowel disease).
• Patients with suspected intestinal bleeding, even in the absence of visible traces of blood.
• Postmenopausal women with anemia of unknown etiology.

• Stool