The sigmoid colon (pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 40 cm in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus sigma + ). This part of the colon normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity.