Abdomen and pelvis: peritoneal covering of the rectum: practice question

A Anatomy question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Anatomy · Abdomen and pelvis: peritoneal covering of the rectum

Sample item

A rigid sigmoidoscope biopsy 4 cm above the anal verge in a man perforates the rectal wall. The patient develops pelvic cellulitis but no peritonitis. Which anatomical fact explains this?

AThe rectum lies entirely extraperitonealBThe lower third of the rectum has no peritoneal coveringCThe peritoneum covers all of the rectal circumferenceDThe rectovesical pouch lies below the perforation

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. The lower third of the rectum has no peritoneal covering

The upper third of the rectum is covered by peritoneum in front and at the sides, the middle third in front only, and the lower third has no covering, lying in the extraperitoneal pelvic tissue. A perforation of the lower rectum thus spreads into the pelvic cellular tissue rather than into the peritoneal cavity.

Option by option

A. The rectum lies entirely extraperitoneal
The upper rectum has peritoneal covering, so the whole organ is not extraperitoneal.
B. The lower third of the rectum has no peritoneal covering (correct)
Correct. The lower rectum is extraperitoneal, so leakage causes pelvic cellulitis.
C. The peritoneum covers all of the rectal circumference
The rectum is not circumferentially covered, only its upper part is partly covered.
D. The rectovesical pouch lies below the perforation
The rectovesical pouch lies above the lower rectum and does not receive spill from a perforation 4 cm from the anal verge.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is B, The lower third of the rectum has no peritoneal covering. The upper third of the rectum is covered by peritoneum in front and at the sides, the middle third in front only, and the lower third has no covering, lying in the extraperitoneal pelvic tissue.

Why is "The rectum lies entirely extraperitoneal" not the answer?

The upper rectum has peritoneal covering, so the whole organ is not extraperitoneal.

Why is "The peritoneum covers all of the rectal circumference" not the answer?

The rectum is not circumferentially covered, only its upper part is partly covered.

Why is "The rectovesical pouch lies below the perforation" not the answer?

The rectovesical pouch lies above the lower rectum and does not receive spill from a perforation 4 cm from the anal verge.

What concept does this question test?

It tests Abdomen and pelvis: peritoneal covering of the rectum in Anatomy. A perforation of the lower rectum thus spreads into the pelvic cellular tissue rather than into the peritoneal cavity.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Abdomen and pelvis: peritoneal covering of the rectum?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.