Colonic varicose veins. Endoscope view of tortuous and distended varicose veins (varices, right) in the colon (main part of the large intestine). The varices are due to high blood pressure (hypertens- ion) due to cirrhosis of the liver. They may rupture, leading to blood in the faeces (melaena). They can be treated by sclerotherapy (injection of a chemical to block the veins) or by the removal of the affected part of the colon.