Labour: brow presentation: 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 · Labour: brow presentation

Sample item

Which diameter presents in a brow presentation and explains why a term baby cannot deliver vaginally?

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

The answer and the reasoning

B. Mentovertical (about 14 cm)

In brow presentation the head is partly extended so the mentovertical diameter (about 14 cm), the longest, tries to engage. Delivery of a term fetus is generally impossible unless the head flexes or extends spontaneously. Caesarean section is the management when persistent.

Option by option

  • A. Biparietal (9.5 cm)

    The biparietal is a transverse diameter and is not the presenting one.

  • B. Mentovertical (about 14 cm) (correct)

    Correct. The mentovertical diameter is too large for the pelvic inlet.

  • C. Submentobregmatic (9.5 cm)

    This engages in face presentation.

  • D. Suboccipitobregmatic (9.5 cm)

    This diameter presents in full flexion.

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.

More OBG questions

Questions about this OBG question

What is the answer to this OBG question?

The best answer is B, Mentovertical (about 14 cm). In brow presentation the head is partly extended so the mentovertical diameter (about 14 cm), the longest, tries to engage.

Why is "Biparietal (9.5 cm)" not the answer?

The biparietal is a transverse diameter and is not the presenting one.

Why is "Submentobregmatic (9.5 cm)" not the answer?

This engages in face presentation.

Why is "Suboccipitobregmatic (9.5 cm)" not the answer?

This diameter presents in full flexion.

What concept does this question test?

It tests Labour: brow presentation in OBG. Delivery of a term fetus is generally impossible unless the head flexes or extends spontaneously. Caesarean section is the management when persistent.

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 Labour: brow presentation?

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.