Human triploidy: association with partial hydatidiform moles and nonmolar conceptuses.

A retrospective pathologic review of nearly 100 spontaneous abortions of cytogenetically verified triploid constitution revealed a majority (86 per cent) falling within the category of partial hydatidiform mole, the chief criteria being focal syncytiotrophoblastic hyperplasia, focal villous edema leading to cistern formation, scalloped outline of villi, and frequent "trophoblastic inclusion" formation. The minority (14 per cent) of the conceptuses were nonmolar with a normal or hypoplastic trophoblast. The triploid fetuses in both groups tended to die at about eight weeks' menstrual age. Intrauterine retention was generally prolonged in the partial moles, whereas nonmolar conceptuses tended to abort within the first trimester, often with live or recently dead fetuses. The problem of two distinct morphologic entities within triploidy remains to be further investigated, especially with respect to the etiologic factors responsible for the division.