Triploid partial molar pregnancy and fetal neural tube defect detected through Down's syndrome screening.

A third case of triploid partial molar pregnancy with fetal neural tube and abdominal-wall defect, detected through maternal serum alphafetoprotein and hCG screening for Down's syndrome is reported. A 23-year-old woman had elevated serum alphafetoprotein and hCG levels at routine screening at the 16th week of gestation. Ultrasound examination suggested a fetal neural tube and abdominal-wall defect with thickened placenta. Amniocentesis was performed. A triploid karyotype (69 XXY) was confirmed with standard cytogenetic analysis. Fetal neural tube and abdominal wall defect was confirmed at the autopsy of the fetus. Placental histology was consistent with a hydatiform mole. When serum alphafetoprotein and hCG are elevated, during screening for Down's syndrome, the possibility of a partial molar pregnancy with fetal malformation should be added to the differential diagnosis.