Blood is taken as direct evidence

Blood in the stool - suspected cancer until proven otherwise

When asked, around three percent of the population reported having seen blood in the toilet bowl in the past six months, and 12 to 15% said they had noticed blood on the toilet paper. Very often this is attributed to hemorrhoids, but this can be a dangerous fallacy. Because "blood in the stool" can also indicate a malignant disease up to colorectal carcinoma and must therefore always be carefully clarified as a finding. The diagnostic examination actually shows a carcinoma as the cause in 4% of cases, and in healthy men who do not present to the doctor because of blood in their stool, but instead state this symptom practically en passant in their anamnesis, rectal bleeding is found with 8% high predictive value for rectosigmoid neoplasia. However, according to the surveys, only 14% of people who notice minimal bright red bleeding from the rectum see a doctor for this.

The finding "blood in the stool" is an expression of bleeding from the lower gastrointestinal tract distal to Treitz's ligament, whereby acute hematochezia lasts less than three days by definition and is associated with circulatory impairment or acute anemia, while chronic bleeding is caused by slow blood loss is defined over several days and can sometimes be accompanied by occult bleeding. A particularly suspicious finding that urgently needs clarification is dark or even black blood on the stool or mixed with it, especially if concomitant mucus admixtures or changes in stool habits are observed.

Not always hemorrhoids as a cause of bleeding

Very often lower gastrointestinal bleeding is actually based on a hemorrhoidal complication, which is evident from the fact that hemorrhoids occur in around 70 to 80% of people in the course of their life. However, this should not lead to hastily inferring a haemorrhoidal disease, because the symptom "blood in the stool" can have a variety of other causes. It can be the result of an anal fissure or anal throat, it can be due to a dermatological disease in the anal area, or it can be caused by a diverticular disease or a chronic inflammatory bowel disease. The cause can also be ischemic colitis, there can be a vascular source of bleeding, i.e. angiodysplasia or another vascular malformation, and the suspicion of columnoplasia must practically always persist until proven otherwise.

This also applies if a patient is already known to have a haemorrhoidal disease. Because hemorrhoids can be detected in 70% of those over 30 years of age and in the worst case do not rule out a malignant occurrence in the intestine. For this reason, practically every bleeding in the lower gastrointestinal tract has to be endoscopic in order to detect and remove a potential carcinoma or its precursors at an early stage.

Rectal bleeding - caution suspected carcinoma

This underlines the result of a prospective colonoscopic examination of patients with hematochezia and a low or average risk of colon cancer: In 8% of the 180 study participants under 45 years of age, polyps in the intestine were found as a precursor to carcinoma. Among the 237 participants over 45 years of age, this percentage was already 26%. The opposite was true for diverticulitis, which was not identified as the cause of bleeding in any of the younger patients but in 19% of the older patients.

The fact that rectal bleeding can be a direct indication of colon carcinoma is underscored by a study of 319 patients with corresponding symptoms, in whom carcinoma was found in 3% of the cases. An increased risk of colorectal carcinoma can generally be assumed beyond the age of 50 and information of a positive family history as well as reports of changed bowel habits and / or unwanted weight loss as well as findings such as anemia, a positive haemocult test or a palpable serve as an alarm signal rectal mass. Regardless of this, the proctologists not only recommend early detection colonoscopy from the age of 55, but also to have digital rectal examinations at the family doctor's regular digital rectal examination once a year, as around 20% of malignant changes in the rectum can be recorded in this way.

source Prof. Dr. Andreas Stallmach, Jena; Prof. Dr. Andreas Sieg, Heidelberg; Prof. Dr. Heinz J. Buhr, Berlin: 4th Coloproctology Symposium for Internists "Blood in the stool - do the hemorrhoids keep coming back?", April 9, 2010, as part of the 116th Congress of the German Society for Internal Medicine in Wiesbaden, organized by Dr . Falk Pharma GmbH, Falk Foundation e.V., Freiburg.


Medical journalist Christine Vetter