Red, cherry or black colour stool may be investigated by upper GI endoscopy, colonoscopy, red cells scintigraphy, angiography, CTscan, enteroscopy and small bowel video capsule.

The cause of bleeding may not be found by any of these tests. For some cases when the cause of bleeding is found embolization may control haemorrhage.

If the cause can not be found and the bleeding continues profoundly, the patient should be operated and a colectomy is performed on the basis that the most common lesion, which bleeds and very often is not found by the routine tests, is angiodysplasia of the right colon.