Obstetric imaging: lemon and banana signs: practice question

A Radiology 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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Radiology · Obstetric imaging: lemon and banana signs

Sample item

A mid-trimester ultrasound shows a scalloped, lemon-shaped fetal head and a banana-shaped cerebellum with an obliterated cisterna magna. What is the associated anomaly?

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

The answer and the reasoning

A. Open spina bifida with Chiari II malformation

In open neural tube defects, downward traction of the hindbrain makes the cerebellum curve (banana sign) and cerebrospinal fluid loss deforms the frontal bones (lemon sign). The cisterna magna is effaced.

Option by option

  • A. Open spina bifida with Chiari II malformation (correct)

    Correct. Lemon and banana signs signal open spina bifida with Chiari II.

  • B. Dandy-Walker malformation

    Dandy-Walker shows an enlarged posterior fossa with vermian hypoplasia.

  • C. Anencephaly

    Anencephaly shows absence of the cranial vault.

  • D. Holoprosencephaly

    Holoprosencephaly shows a single ventricle and facial anomalies.

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 Radiology question

What is the answer to this Radiology question?

The best answer is A, Open spina bifida with Chiari II malformation. In open neural tube defects, downward traction of the hindbrain makes the cerebellum curve (banana sign) and cerebrospinal fluid loss deforms the frontal bones (lemon sign).

Why is "Dandy-Walker malformation" not the answer?

Dandy-Walker shows an enlarged posterior fossa with vermian hypoplasia.

Why is "Anencephaly" not the answer?

Anencephaly shows absence of the cranial vault.

Why is "Holoprosencephaly" not the answer?

Holoprosencephaly shows a single ventricle and facial anomalies.

What concept does this question test?

It tests Obstetric imaging: lemon and banana signs in Radiology. The cisterna magna is effaced.

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 Obstetric imaging: lemon and banana signs?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology 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.