Oesophageal varicose veins. Endoscope view of widened (varicose) veins in the oesophagus due to portal hypertension (high blood pressure). Oesophageal varices occur when liver damage causes high blood pressure in the portal vein, which takes blood from the spleen, intestines and stomach to the liver. This causes the nearby veins in the oesophagus to widen. The veins may rupture, causing bouts of vomiting blood and black faeces. Surgery to reduce the pressure in the portal vein may effect a cure, or the veins can be injected with a sclerosant, which permanently clots them.