QuestionSBA
QuestionChoice
The obstetrician is concerned about the possibility of a neural tube defect. AFP is mainly produced by the foetal liver. Rises in AFP may indicate leakage through an open neural tube defect. The lemon sign can be detected on the scan due to the decrease in the intraspinal pressure which in turn decreases the intracranial pressure resulting in the flattening or scalloping inwards of the frontal bones giving us the lemon sign. The lemon sign is only present until 24 weeks.
10026485
a
Lemon sign
QuestionChoice
The double bleb sign is the earliest sign of an embryo on ultrasound. The two blebs represent the amniotic sac adjacent to the yolk sac. It would not explain the increased AFP.
10026487
c
Double bleb sign
QuestionChoice
This would be found on abdominal x-ray in those with a diagnosis of sigmoid volvulus. It would not be a cause for isolated AFP increase and has no relevance to pregnancy/ultrasound.
10026486
b
Coffee bean sign
QuestionChoice
Nuchal translucency is the collection of fluid behind the foetal neck. It forms part of the down syndrome screening programme. In Down Syndrome. AFP is reduced as opposed to elevated.
10026488
d
Nuchal translucency
QuestionChoice
The crown-rump length is useful in estimating the gestational age. It has no relevance to the isolated AFP increase.
10026489
e
Crown-rump length
Concept
Chapter
2693
5895
Development of the spinal cord
Topic
171
Embryology
17695
A 24-year-old pregnant female attends an appointment with her obstetrician following an isolated elevated alpha-fetoprotein (AFP) level detected on a blood test. The obstetrician is concerned about foetal development and would like to perform an ultrasound.

What sign is the obstetrician most likely looking for?
a