Colonoscopy is a form of endoscopy used to view the large intestine. The intestinal lining initially appears smooth and normal, but a bulging, discolored, and abnormal growth is later seen. Next, small clippers attached to a metal wire are inserted through the endoscope and used to grab the growth. A tissue sample is removed for biopsy. The small amount of blood seen is normal after a biopsy.
Courtesy of Jerome D. Waye, MD.