Rectum

The rectum is part of the distal part of the gastrointestinal tract; it is between the sigmoid colon and anus.

Definition

Abdominoperineal resection specimen showing the rectum.

Pathologist generally agree that: the rectum starts/sigmoid ends at the place where serosa ends on the posterior aspect of the bowel. In other words, the peritoneal reflection is the landmark that separates the sigmoid colon and rectum.

Notes on the definition

• On a practical level, the definition is not easy to apply from the lumen, i.e. the definition is not practical in the endoscopic context.

• • There are several definitions for the rectum.
    • In a survey of surgeons:
    • 67% defined it by an anatomical landmark
      • 35% of all respondants considered the peritoneal reflection the proximal boundary of the rectum.
    • 30% defined the proximal boundary as a distance from the anal verge.

See also

• Colon.