Inflammatory polyps in ulcerative colitis, endoscope view. Ulcerative colitis is an inflammation and ulceration of the lining of the colon. It causes bloody diarrhoea and abdominal pain. Its cause is not known. Polyps are a common complication of colitis as they develop as a regenerative response to the inflammation and ulceration of the mucosa. There are numerous polyps here, termed polyposis. Treatment may require removal of all or part of the colon (colectomy). These polyps are in the transverse colon.