Prenatal diagnosis of a tetraploid fetus.

A tetraploid fetus with an unusual facial appearance and multiple congenital anomalies (large cerebral lateral ventricles; lung, cardiac, and genital abnormalities) is reported. Chromosome analysis was performed on amniocytes and fetal blood lymphocytes. A comparison is made with other reported cases (nine liveborn infants and one 17.2-week-old fetus).