Triploid fetus: an important consideration in the evaluation of very high maternal serum alpha-fetoprotein.

Two patients referred for evaluation of very high maternal serum alpha-fetoprotein (10-20 multiples of the median) were carrying triploid fetuses with placentas showing features of partial hydatidiform mole. The diagnosis of fetal triploidy should be considered when there is a very high maternal serum alpha-fetoprotein and no ultrasound evidence of open neural tube defect, ventral wall defect, or any other explanation. Therefore, chromosomal analysis of amniotic fluid cells in such cases is essential.