Triploid partial molar pregnancy detected through maternal serum alpha-fetoprotein and HCG screening.
BACKGROUND
Screening for Down syndrome using maternal serum alpha-fetoprotein (MSAFP) and hCG, with or without unconjugated estriol (E3), has become standard practice in much of the United States. When both MSAFP and hCG are elevated, the possibility of a partial molar pregnancy with fetal neural tube or abdominal-wall defect should be added to the differential diagnosis, as illustrated by this case.


METHODS
A 22-year-old woman had elevated MSAFP and hCG levels on routine screening at 16 weeks' gestation. Ultrasound examination suggested a neural tube defect and a thickened placenta. Amniocentesis was performed. She very rapidly developed preeclampsia. Fluorescence in situ hybridization showed three distinct spots for the three probes tested. A triploid karyotype was confirmed with standard cytogenetic analysis. The fetus had an open neural tube defect, and placental pathology was consistent with a partial hydatidiform mole.


CONCLUSIONS
A possible partial molar pregnancy with abdominal-wall or open neural tube defect should be added to the differential diagnosis for interpreting Down syndrome screens when both MSAFP and hCG are elevated. A presumptive diagnosis of triploidy using fluorescence in situ hybridization was important in the management of this pregnancy.
Harper
M A
MA
Department of Obstetrics and Gynecology, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina.
Ruiz
C
C
Pettenati
M J
MJ
Rao
P N
PN
D000328:Adult; D006063:Chorionic Gonadotropin / Q000097:blood*; D002869:Chromosome Aberrations; D003937:Diagnosis, Differential; D004314:Down Syndrome / Q000175:diagnosis; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis; D006801:Humans; D006828:Hydatidiform Mole / Q000150:complications / Q000175:diagnosis* / Q000235:genetics; D007621:Karyotyping; D011225:Pre-Eclampsia / Q000150:complications; D011247:Pregnancy; D011296:Prenatal Diagnosis; D016135:Spinal Dysraphism / Q000175:diagnosis; D014594:Uterine Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000235:genetics; D000509:alpha-Fetoproteins / Q000032:analysis*
D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins