Ulcerative colitis. Endoscopic view of the interior of a patient's distal colon (large intestine) affected by ulcerative colitis (UC), showing ulceration (white areas), inflammation and bleeding (red). UC is an inflammation and ulceration of the colon that causes bloody diarrhoea and abdominal pain. The cause is not known. Treatment is with anti-inflammatory drugs, and in severe cases surgical removal of the colon.