Question
The condition shown in the image below can be diagnosed by USG as early at which week of gestation?
A. 5 weeks of gestation.
B. 8 weeks of gestation.
C. 10 weeks of gestation.
D. 14 weeks of gestation.
Show Answer
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Correct Answer » C
Explanation
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Ans:C. 10 weeks of gestation.
The condition shown in the picture above represents anencephaly.
Anencephaly
- It is characterised by absence of the cranial vault and cerebral hemispheres.
- It is the most common type of neural tube defect.
- Occurs when the rostral (head) end of the neural tube fails to close, usually between the 23rd and 26th day following conception
- Anencephaly may be sonographically detectable as early as 10 weeks.
- Ultrasound has an accuracy of approximating 100% at 14 weeks
Features seen are:
- no parenchymal tissue is seen above the orbits and calvarium is absent: parts of the occipital bone and mid brain may be present
- less than expected value for crown rump length (CRL)
- a “frog eye” or “mickey mouse” appearance may be seen when seen in the coronal plane due to absent cranial bone/brain and bulging orbits.
- may show evidence of polyhydramnios: due to impaired swallowing
