Normal pregnancy: ureteric dilatation: practice question

A OBG 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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OBG · Normal pregnancy: ureteric dilatation

Sample item

An ultrasound at 28 weeks in an asymptomatic woman shows mild dilatation of the right renal pelvis and ureter, greater than on the left. What is the explanation?

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

The answer and the reasoning

B. Progesterone-induced smooth muscle relaxation and compression at the pelvic brim, more on the right

Physiological hydroureteronephrosis arises from hormonal relaxation and mechanical compression at the pelvic brim, and it is more marked on the right because of the dextrorotation of the uterus and the cushioning effect of the sigmoid on the left. It is an expected finding and needs no treatment, though it predisposes to pyelonephritis.

Option by option

  • A. Vesicoureteric reflux caused by a left-sided uterus

    Reflux is not the mechanism of this asymptomatic finding.

  • B. Progesterone-induced smooth muscle relaxation and compression at the pelvic brim, more on the right (correct)

    Correct. Hormonal relaxation plus brim compression, worse on the right, is the normal pattern.

  • C. Congenital pelviureteric junction obstruction

    Congenital obstruction is not the usual cause of mild bilateral physiological dilatation.

  • D. Compression of the left ureter by the dextrorotated uterus

    The dextrorotated uterus compresses the right ureter, not the left.

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 OBG question

What is the answer to this OBG question?

The best answer is B, Progesterone-induced smooth muscle relaxation and compression at the pelvic brim, more on the right. Physiological hydroureteronephrosis arises from hormonal relaxation and mechanical compression at the pelvic brim, and it is more marked on the right because of the dextrorotation of the uterus and the cushioning effect of the sigmoid on the left.

Why is "Vesicoureteric reflux caused by a left-sided uterus" not the answer?

Reflux is not the mechanism of this asymptomatic finding.

Why is "Congenital pelviureteric junction obstruction" not the answer?

Congenital obstruction is not the usual cause of mild bilateral physiological dilatation.

Why is "Compression of the left ureter by the dextrorotated uterus" not the answer?

The dextrorotated uterus compresses the right ureter, not the left.

What concept does this question test?

It tests Normal pregnancy: ureteric dilatation in OBG. It is an expected finding and needs no treatment, though it predisposes to pyelonephritis.

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 Normal pregnancy: ureteric dilatation?

Learn management algorithms as steps: PPH, eclampsia, ectopic pregnancy. Then use the flashcards and the other OBG 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.