A colonoscopy is a medical procedure where a long, thin tube with a tiny camera on the end is inserted into the person's rectum and passed through the large intestine. The camera allows the doctor to see the inside of the intestine and look for any problems, such as inflammation, bleeding, or polyps. If the doctor sees any polyps, they may use a tool on the endoscope to remove them or take a biopsy (a small sample of tissue) to check for cancer. Band ligation is a procedure where the doctor ties a small rubber band around a polyp to cut off the blood supply to the polyp. This causes the polyp to fall off and be passed out of the body in the person's stool.