They usually are present with other symptoms. An inflamed rectum is usually caused by an infection. The cause of an inflamed colon is usually unknown. It can cause rectal bleeding. Polyps are often found before the cancer is diagnosed.
Polyps are small growths from the inner lining of the colon.
They may cause minor bleeding. This makes screening for blood in the stool a useful tool for early detection of colon cancer. The test can detect small amounts of blood that would typically go unnoticed. Bleeding that occurs higher in the intestine than the colon may be maroon or black. Peptic ulcers cause black or tarry stools.