Chapter 9: Diseases of the Colon and Rectum

The human colon—or large intestine—is primarily responsible for absorbing remaining water from indigestible food matter that has passed through the small intestine, maintaining the water balance in the body, and absorption of some vitamins. The final section of the luminal digestive tract, the rectum and anus, eliminates wastes from the body. Diseases involving the colon and rectum are diverse and include anatomic conditions (e.g., diverticular disease, fistulas, fecal incontinence), blood flow or vascular disorders (e.g., colonic ischemia, angioectasias, hemorrhoids), conditions related to the gut microflora or immune dysfunction (e.g., inflammatory bowel disease, appendicitis), or treatment-related disorders (e.g., radiation colitis).