Embryology: renal ascent: 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 · Embryology: renal ascent

Sample item

A 25-year-old woman with Turner syndrome (45,X) has recurrent urinary infections. Imaging shows fused lower poles of both kidneys lying low in the abdomen, with the isthmus passing in front of the aorta. Why do the kidneys lie low?

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

The answer and the reasoning

B. Their ascent was arrested when the isthmus caught under the inferior mesenteric artery

In horseshoe kidney the lower poles fuse before ascent, and the isthmus is held up by the root of the inferior mesenteric artery. The kidney therefore remains low and has abnormal rotation and drainage that predisposes to infection and stones. It is associated with Turner syndrome.

Option by option

  • A. Their ascent was arrested by the superior mesenteric artery

    The superior mesenteric artery lies higher and does not trap the isthmus.

  • B. Their ascent was arrested when the isthmus caught under the inferior mesenteric artery (correct)

    Correct. The inferior mesenteric artery holds back the fused isthmus.

  • C. The ureteric buds failed to reach the metanephric blastema

    Failure of the ureteric bud to reach the blastema would cause renal agenesis.

  • D. The kidneys remained attached to the mesonephros

    The kidney is a metanephric derivative and separates from the mesonephros during development.

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.

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Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is B, Their ascent was arrested when the isthmus caught under the inferior mesenteric artery. In horseshoe kidney the lower poles fuse before ascent, and the isthmus is held up by the root of the inferior mesenteric artery.

Why is "Their ascent was arrested by the superior mesenteric artery" not the answer?

The superior mesenteric artery lies higher and does not trap the isthmus.

Why is "The ureteric buds failed to reach the metanephric blastema" not the answer?

Failure of the ureteric bud to reach the blastema would cause renal agenesis.

Why is "The kidneys remained attached to the mesonephros" not the answer?

The kidney is a metanephric derivative and separates from the mesonephros during development.

What concept does this question test?

It tests Embryology: renal ascent in Anatomy. The kidney therefore remains low and has abnormal rotation and drainage that predisposes to infection and stones. It is associated with Turner syndrome.

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 Embryology: renal ascent?

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.