Labour and delivery: ventouse cup placement: 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 and delivery: ventouse cup placement

Sample item

When applying a vacuum cup, its centre should lie over the flexion (pivot) point. Where is this located?

AOn the sagittal suture 3 cm in front of the anterior fontanelleBOn the anterior fontanelleCAt the posterior fontanelle itselfDOn the sagittal suture about 3 cm in front of the posterior fontanelle

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

The answer and the reasoning

D. On the sagittal suture about 3 cm in front of the posterior fontanelle

The pivot point lies on the sagittal suture about 3 cm anterior to the posterior fontanelle. A cup placed over it promotes flexion and uses the smallest presenting diameter. A cup placed away from it causes deflexion and a higher chance of failure and fetal scalp injury.

Option by option

A. On the sagittal suture 3 cm in front of the anterior fontanelle
A point anterior to the anterior fontanelle lies on the forehead and brow, and would extend the head.
B. On the anterior fontanelle
Placing the cup on the anterior fontanelle promotes extension and risks failure.
C. At the posterior fontanelle itself
The cup centred on the posterior fontanelle itself lies too far back and encourages deflexion.
D. On the sagittal suture about 3 cm in front of the posterior fontanelle (correct)
Correct. The pivot point is 3 cm anterior to the posterior fontanelle on the sagittal suture.

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 OBG question

What is the answer to this OBG question?

The best answer is D, On the sagittal suture about 3 cm in front of the posterior fontanelle. The pivot point lies on the sagittal suture about 3 cm anterior to the posterior fontanelle.

Why is "On the sagittal suture 3 cm in front of the anterior fontanelle" not the answer?

A point anterior to the anterior fontanelle lies on the forehead and brow, and would extend the head.

Why is "On the anterior fontanelle" not the answer?

Placing the cup on the anterior fontanelle promotes extension and risks failure.

Why is "At the posterior fontanelle itself" not the answer?

The cup centred on the posterior fontanelle itself lies too far back and encourages deflexion.

What concept does this question test?

It tests Labour and delivery: ventouse cup placement in OBG. A cup placed over it promotes flexion and uses the smallest presenting diameter. A cup placed away from it causes deflexion and a higher chance of failure and fetal scalp injury.

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 and delivery: ventouse cup placement?

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.