Colon sigmoideum

The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus.

It forms a loop that averages about 35–40 centimetres (14–16 in) in length.

The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus sigma + -oid).

This part of the colon normally lies within the pelvis, but due to its freedom of movement it is liable to be displaced into the abdominal cavity.