Why Patients With Haemorrhoids Bleed in Their Stools

The above picture shows a view of the lower rectum at colonoscopy. It is obvious the prominent dilated veins in the wall of the rectum. These veins are bigger than usual and appears greenish-blue in colour. Dilated vascular systems always carry more blood flow than otherwise.

Patients with haemorrhoids that present with rectal bleeding always have these dilated veins in the lower rectal walls. These dilated blood vessels may rupture especially during bowel motion due to sudden increase in pressure within the blood vessels. Bleeding tend to be self-limiting due to minute rupture and the vessels will get clotted by itself quite easily.

Why these dilated blood vessels occur in the first place in patients that suffer common haemorrhoids is not well understood. It may be related to the stagnation of blood flow due to persistent intraabdominal pressure preventing normal blood flow out off the rectal wall area. These may explain the frequent occurence of common haemorrhoids in patients that always constipate and in pregnant ladies.

One unique medical condition that give rise to the dilated veins above is the varicose veins of the recto-anal region due to the new blood vessels connections between the systemic blood vessels of the anal region with the portal blood vessels of the lower rectum. This condition usually occur in patients with chronic liver disease and cirrhosis. Varicose veins in the recto-anal region is less common than the varicose veins(varices) in the oesophago-gastric region which presents with vomiting of blood.