Triploidy in 40 human spontaneous abortuses: assessment of phenotype in embryos

Forty human spontaneous abortuses were identified as triploid, 34 by karyotype and 6 by DNA measurement. Of the 40, 26 were embryos of 5 to 7 weeks' developmental age, 6 were intact empty sacs, 4 were early growth-disorganized embryos, and 4 were fetuses. In an attempt to determine the extent to which embryonic phenotype reveals triploid karyotype, the phenotypes of the 26 triploid embryos were compared with those of the 40 embryos of known nontriploid karyotype identified in larger study of consecutive spontaneous abortuses. Each embryo was scored for presence or absence of each of 4 abnormal phenotypic features: retarded limb development, facial dysplasia, subectodermal hemorrhage, and cystic chorionic villi. Whereas this combination of features was found in a few abortuses with normal or trisomic karyotype, it was both common and most frequent with triploidy. Approximately half (12 of 22) of the triploid embryos had at least 3 of the features. Conversely, among assessable embryos of known karyotype, four fifths (12 of 15) of those with at least 3 of the 4 abnormal features were triploid. Thus, while not definitive, such phenotypic information can be used with caution in counseling for subsequent pregnancies.