A sigmoid colon resection is when the S-shaped lower portion of the large intestine is wholly or partially removed and then attached to the rectum, says Ohio State University Wexner Medical Center. The rectum is the last six inches of the colon, says InnerBody.
The sigmoid colon may be removed for several reasons, according to Ohio State University Wexner Medical Center. They include suspicious polyps found in the colon, cancer, irritable bowel disease and bleeding. Other reasons are a blockage in the sigmoid colon and diverticulitis, an inflammation of the pouches called diverticulae in the colon wall, says WebMD. Volvulus is another reason for sigmoid colon resection. This happens when the colon twists and cuts off the flow of blood, says MedlinePlus.