Antenatal care: fetal lung maturity: 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 · Antenatal care: fetal lung maturity

Sample item

Which finding in amniotic fluid indicates fetal lung maturity?

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

The answer and the reasoning

C. Lecithin to sphingomyelin ratio above 2

An L:S ratio of 2 or more and the presence of phosphatidylglycerol indicate adequate surfactant. Diabetes can delay phosphatidylglycerol, so presence of PG is more reassuring. A low ratio indicates risk of respiratory distress syndrome.

Option by option

  • A. Absent phosphatidylglycerol

    Absent phosphatidylglycerol suggests immaturity.

  • B. Bilirubin level above 0.1 optical density units

    Bilirubin optical density relates to Rh alloimmunisation, not lung maturity.

  • C. Lecithin to sphingomyelin ratio above 2 (correct)

    Correct. A ratio of 2 or more shows mature surfactant production.

  • D. Lecithin to sphingomyelin ratio below 1

    A ratio below 1 indicates immaturity.

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 C, Lecithin to sphingomyelin ratio above 2. An L:S ratio of 2 or more and the presence of phosphatidylglycerol indicate adequate surfactant.

Why is "Absent phosphatidylglycerol" not the answer?

Absent phosphatidylglycerol suggests immaturity.

Why is "Bilirubin level above 0.1 optical density units" not the answer?

Bilirubin optical density relates to Rh alloimmunisation, not lung maturity.

Why is "Lecithin to sphingomyelin ratio below 1" not the answer?

A ratio below 1 indicates immaturity.

What concept does this question test?

It tests Antenatal care: fetal lung maturity in OBG. Diabetes can delay phosphatidylglycerol, so presence of PG is more reassuring. A low ratio indicates risk of respiratory distress 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 Antenatal care: fetal lung maturity?

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.