The anorectum is the terminal portion of the gastrointestinal tract. It is embedded
in the osseous pelvis and surrounded by urogenital organs as well as muscular, ligamentous,
and connective tissue structures. It is the functional unit that maintains fecal continence
by providing both a stopper-equipped reservoir and a controlled expulsion mechanism
for feces. The rectum is the last and partially extraperitoneal segment of the large
intestine. It starts at the rectosigmoid junction and continues through the pelvic
floor into the anal canal. The nonmobilized rectum is characterized by three distinct
endoluminal curves. The resulting folds that are seen on endoscopy are referred to
as the valves of Houston. Definitions of where the sigmoid colon ends and the rectum
begins include: (1) a distance of fifteen centimeters above the anal verge, (2) the
position of the peritoneal reflection, and (3) the level of the sacral promontory.
We maintain that the most useful landmark from a functional as well as surgical viewpoint
is the confluence of the teniae coli at the rectosigmoid junction [
[1]
]. Because this anatomic reference point cannot be visualized endoscopically, the National
Cancer Institute has recently defined the rectum as the last twelve centimeters above
the anal verge for the purpose of uniformity in clinical trials [
[2]
]. This definition is useful in preparing for a low anterior resection versus a sigmoid
resection, particularly when measured with a rigid sigmoidoscope.To read this article in full you will need to make a payment
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© 2002 Elsevier Science (USA). Published by Elsevier Inc. All rights reserved.
