What is a stool examination?
Human feces provide information about the condition of the digestive tract through their color, mass, hardness and odor. Normally, feces consist mainly of water, food residues, bacteria and degraded mucosal cells. It gets its color from broken down bile pigments.
If there are red blood admixtures visibly on the stool, they probably come from mid to lower intestinal segments, such as hemorrhoids, polyps or diverticula (protrusions of the intestinal wall). A black, shiny stool (tarry stool) results from bleeding in the upper digestive tract (such as esophagus, stomach): The hemoglobin in the blood is broken down by contact with stomach acid and then turns the stool black.
When is a stool examination performed?
A stool examination is always necessary if there are unclear complaints in the area of the digestive tract over a longer period of time, such as abdominal pain, cramps, diarrhea or constipation. Particularly in the case of digestive complaints after a trip abroad, a stool examination can provide information about parasites, bacteria or viruses that one has caught on the way.
For people over the age of 50, a stool analysis (examination for blood in the stool) is recommended as part of the early detection of colorectal cancer.
What is done during a stool analysis?
For the stool test, the doctor gives the patient a plastic tube with a small spatula attached to the screw cap. With it he has to take small samples from three different places of the stool and put them into the tube. The sealed tube is then given to the doctor, who sends it to a laboratory for evaluation.
Fecal occult blood test
Immunological stool test (i-FOBT)
In medical diagnostics, the immunological stool test has replaced the previously used hemoccult test. Both can detect minute traces of blood in the stool. While the conventional hemoccult test uses a biochemical color reaction, the immunological stool test uses antibodies.
The advantage of the immunological blood test is that it detects polyps or tumors more reliably than the old hemoccult test. And it is less likely to sound a false alarm than the hemoccult test, which is positive even if the patient has eaten raw meat, blood sausage, or vegetables containing peroxidase (such as cauliflower and radishes).
Such false-positive results can cause the patient great concern and lead to unnecessary, stressful follow-up examinations. The immunological stool test, on the other hand, does not react to these foods, but only to human blood.
Hemoccult test (Guaiac test)
The old method for detecting occult blood in stool, the hemoccult test, is also called the guaiac test. This biochemical test uses a special solution to detect the red blood pigment hemoglobin in the stool sample. Unlike the Immunological Stool Test, this test also reacts to animal blood and foods containing peroxidase (see above).
Whether Immunological Stool Test or Hemoccult Test: If the result is positive, the physician will order further tests and a colonoscopy. This will help determine the source of the occult blood (polyps, colon cancer, etc.).
M2-PK stool test
Helicobacter stool test
A Helicobacter stool test can detect antibodies against the stomach germ Helicobacter pylori. The test is performed if gastritis or duodenal ulcer are suspected – diseases that are often caused by the bacterium. If the stool test is positive, i.e. a Helicobacter infection is present, this is treated with medication.
What are the risks of a stool examination?
There are no risks associated with a stool examination. You yourself do not come into contact with the feces, to collect the stool sample you take a spatula and with this you put the stool sample into the sample tube, which is then tightly sealed and passed on to the doctor for stool analysis.
