pelvic colon

The sigmoid colon is the final section of the large intestine, connecting the descending colon to the rectum. It is S-shaped, hence its name from the Greek letter sigma. Its primary function is to store fecal waste until it is ready for elimination from the body.1

The sigmoid colon's diameter is typically about one inch when contracted, but its size can vary depending on the amount of waste it holds. Its inner lining secretes mucus, which aids in lubrication, and its muscle layers help move waste towards the rectum. Fecal matter can remain in the sigmoid colon for seven hours or more, often being expelled when new waste enters this section. The large intestine, including the sigmoid colon, plays a crucial role in absorbing water and electrolytes, and in storing indigestible matter that forms feces.12