Blood in Faeces

author/s: Dr Mª Carmen Peña Cala

The appearance of the visualised blood might point us towards a series of causes that might be responsible for the bleeding.


What makes the blood appear after defecation?

On most occasions, the patient will observe reddish blood that can appear after the defecation, embedded in the stools, or when the patient is using toilet paper. This type of bleeding is characteristic of anal pathology, as with haemorrhoids or anal fissures. Diagnosis must be confirmed by means of a careful anal exploration that will logically include a rectal digital examination and a rectoscopy. In the case that no diagnosis is established, the possibility of bleeding higher up in the colonic tract should be considered.


What causes the blood to be mixed with the faeces?

With less frequency, the patient can have faeces mixed with blood. This will compel us to explore the upper tract of the colon and will require an anal exploration plus colonoscopy. This technique will allow us to observe other lesions such as polyps of the colon, colon cancer or vascular lesions or intestinal inflammatory disease (such as ulcerous colitis) that can cause a bleeding of this type.


What should I do if the faeces have a tar-like appearance?

There is the possibility that the patient observes very black, sticky, tar-looking stools, characteristics of bleeding higher up the tract, normally originating in the stomach. This finding will require a gastroscopy to rule out a bleeding ulcer, for instance, a gastric ulcer.


When should I go to the doctor?

The appearance of the stools will guide us as to the origin of the bleeding. One should not forget that a patient with haemorrhoids can also have a polyp or colon cancer. For this reason, and especially in patients over 50 or with a personal or familial history of polyps or colon cancer, it is advisable to assess the condition of the colon via endoscopy. In younger individuals and with no relevant past history, a simple anal exploration can serve as a diagnostic tool. However, if the bleeding persists, a colonoscopy should be done.

With the above in mind, if a patient sees blood repeatedly in the stools, it would be advisable to seek medical attention immediately.