Extremely high maternal serum alpha-fetoprotein levels at second-trimester screening.

Area of Science:

• Maternal-fetal medicine
• Prenatal screening
• Obstetrics

Background:

• Maternal serum alpha-fetoprotein (MSAFP) screening is a standard prenatal test.
• Elevated MSAFP levels can indicate various pregnancy complications, including open neural tube defects (NTDs).
• Understanding the implications of significantly elevated MSAFP (≥8 multiples of the median) is crucial for patient counseling and management.

Purpose of the Study:

• To investigate the outcomes of pregnancies with significantly elevated maternal serum alpha-fetoprotein (MSAFP) levels (≥8 multiples of the median).
• To determine the positive predictive value of high MSAFP for neural tube defects (NTDs).
• To identify the spectrum of fetal anomalies and obstetric complications associated with elevated MSAFP.

Main Methods:

• Retrospective analysis of 40,676 screened pregnancies.
• Focused examination of 44 pregnancies with MSAFP levels ≥8 multiples of the median (MoM).
• Utilized ultrasound for initial evaluation and assessed pregnancy outcomes, including fetal anomalies, survival rates, and obstetric complications.

Main Results:

• 82% of elevated MSAFP cases had an identifiable cause on initial ultrasound.
• Major fetal anomalies were present in 45% of fetuses; 25% experienced fetal death before 20 weeks.
• The positive predictive value for NTDs was 22.7%; most high MSAFP cases involved major anomalies or early fetal demise.

Conclusions:

• Significantly elevated MSAFP (≥8 MoM) is predominantly associated with major structural fetal anomalies or early fetal death, not solely NTDs.
• Pregnancies with high MSAFP levels often involve significant obstetric complications, even in live births.
• Ultrasound plays a critical role in identifying the cause of MSAFP elevation and guiding management.