Diagnosis of a triploid fetus at genetic amniocentesis

Nearly 20% of spontaneously aborted fetuses with chromosomal errors have been shown to have a triploid karyotype. Such a fetus is rarely encountered during the course of an amniocentesis at midtrimester. Because amniotic fluid cell polyploidy is an occasional finding among normal fetuses at midtrimester, the following report illustrates the importance of gathering corroborative evidence of an affected fetus before arriving at a prenatal diagnosis.