Question
The condition shown in the picture above is best diagnosed using ?
A. Maternal serum alpha feto protein.
B. Amniotic fluid alpha feto protein.
C. USG.
D. X-ray.
Show Answer
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Correct Answer » C Explanation |
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Ans:C. USG.
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
Pathological features :
- Forebrain and midbrain are absent.
- Cerebellum and Hindbrain are less involved or completely spared.
- Base of skull and facial bones are not affected.
- Pituitary gland is either absent or hypoplastic.
- As a result : Adrenal gland is diminished in size. Such fetuses have bulging eyes, short neck and a large tongue.
Complications caused by Anencephaly during Pregnancy :
- Polyhydramnios : seen in 35% cases.
- Preterm labour : due to associated polyhydramnios.
- Malpresentation : Face presentation (Most common) and Breech presentation. Rather most common fetal anomaly responsible for face presentation is Anencephaly
Tendency for post maturity.
Complications during Labour
- Shoulder dystocia : Most common complication of anencephaly during labour.
Obstructed labour
- Risk of recurrence is 5% after one affected child and 13% after two affected children.
Cause:
- Folic acid deficiency may play a role in anencephaly.
- It is recommended that all women of child-bearing age consume 0.4 mg of folic acid daily,especially those attempting to conceive or who may possibly conceive, as this can reduce the risk to 0.03%.
Diagnosis of Anencephaly/ NTD in brief:
- Best screening test for NTD : Maternal serum Alpha protein (between 14 and 22 weeks, best at 16 weeks).
- Best marker for NTD/Open spina bifida / Anencephaly is Acetyl cholinesterase.
- Best investigation for Anencephaly – ultrasound.
- 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