Blood in the stool: what causes it and what diseases it may be associated with

By Cristiano Antonino On Jun 9, 2022

It may happen that, after evacuating, one notices the presence of blood in the stool. This can happen for very different causes and although blood can be a cause for concern, its presence is not necessarily an alarm bell

Blood in the stool: what are the causes?

When one notices the presence of blood in the stool, it is usually a problem in the digestive tract. In particular, there may be:

varices
damage to the wall of the oesophagus;
ulcers;
gastritis;
trauma or the presence of foreign bodies;
polyps or tumours;
diverticulitis;
haemorrhoids;
chronic inflammatory bowel disease;
infections;
intestinal ischaemia/infarction;
anal fissures.

Blood in the stool can be linked to various diseases, from colitis to haemorrhoids to colorectal cancer.

What to do when there is blood in the stool?

The presence of blood in the stool is not a sign to be underestimated, whether it is haematochezia (i.e. stools mixed with bright red blood, which can be detected when one cleans oneself after defecating), rectorrhagia (a more important anal bleeding), or melena (dark-coloured, semi-solid stools).

In these cases it is always a good idea to consult the doctor, who – if he or she considers it appropriate – will suggest the most suitable investigations and refer the patient to a specialist.

Occult blood in the faeces and colorectal cancer

Colorectal cancer develops as a result of uncontrolled proliferation of epithelial cells of the mucous lining of the inner part of the colon or rectum.

In its early stages, colorectal cancer is usually asymptomatic. Symptoms that should not be underestimated, however, include bleeding from the rectum or the presence of blood on the toilet paper after evacuation.

The first stage of diagnosis of colorectal cancer is based on the search for occult blood in the faeces, a laboratory test to be performed every two years, starting at the age of 50. If the result is positive, the patient will be referred for a colonoscopy, the instrumental examination that can confirm or exclude the presence of a tumour or precancerous lesions (polyps) responsible for the positive test.