What is an occult blood positive

Blood in the stool

An optically invisible addition of blood to the stool is called

  • "Occult blood" ("occult blood") referred to in the stool.

This examination for occult blood in the stool is of great importance with regard to benign or malignant tumors in the area of ​​the lower digestive tract - including the large intestine (colon) and rectum.

In general, caution is advised when assessing the color of the chair. Because a visible one Red discoloration of the stool does not have to mean an addition of blood, but can be related to the previously consumed food:

  • E.g. consumption of red beets or dishes with a high content of red paprika powder (goulash, rice meat, etc.).

NoteColorectal cancer is the second most common malignant tumor in women and men. From the age of 50, an annual examination for occult blood in the stool is therefore recommended.

The stool occult blood test can be performed in the hospital or at home. The patient has to fill special test letters with small stool samples. Overall, the stool samples should
  • on three consecutive days,
  • from two different places on the chair
  • can be applied to the appropriate places on the test booklet.

Before and during the investigation period, no raw meat dishes (tartare, half-raw steaks), black pudding or other blood-containing food (Styrian blood summer) may be eaten. In addition, the consumption of vitamin C (ascorbic acid) should be avoided (false negative results possible).

Most hemoccult test systems work on a so-called gujak resin base. After adding a suitable developer (hydrogen peroxide solution) to the dried stool in the test letter, the sample turns blue if there is blood or blood components in the stool.