Exxcellence pearls: elevated maternal AFP

Question 0

Where is fetal alpha-fetoprotein produced?

Answer 0

Fetal liver

Question 1

When do levels of maternal serum alpha-fetoprotein rise?

Answer 1

Second trimester

Question 2

How are abnormal AFP results described?

Answer 2

Multiples of the median. Levels greater than 2.5 for specific week of gestation are considered elevated.

Question 4

What factors are sometimes used to modify calculations of AFP multiples of the median?

Answer 4

Maternal weight, race, diabetes mellitus

Question 4

How is maternal AFP affected by a fetus with Down syndrome?

Answer 4

Reduced by approximately 25%

Question 5

What does elevated AFP typically suggest?

Answer 5

Open fetal defect such as spina bifida, anencephaly, or abdominal wall defect

Question 6

What can cause false positives for AFP?

Answer 6

Under estimation of gestational age, multi-fetal pregnancy, fetomaternal hemorrhage.

Question 7

How should elevated AFP be followed up?

Answer 7

Ultrasound. Historically amniocentesis for amniotic fluid AFP was performed.

KB fetal cells staining should be considered for Rh negative women.

Question 8

What ultrasound findings are suggestive of spina bifida?

Answer 8

“Lemon sign” and “banana sign”.