Rare finding of 2n/4n mixoploidy in mother and fetus with severe immune hydrops.

The findings of diploid-tetraploid mosaicism in cultured amniotic fluid cells is considered a culture artifact. On rare occasions its presence indicates a chromosomally abnormal fetus with multiple congenital defects. We present here a patient who in her previous pregnancies had delivered one hydrops and two macerated fetuses. The reported pregnancy also resulted in a fetus with severe hydrops. Cytogenetic analysis of cultured amniotic fluid cells revealed diploid-tetraploid mosaicism in the fetus also confirmed in fetal cord blood and skin fibroblasts. Chromosomal analysis of the parents revealed mixoploidy in the mother. These findings are extremely important for prenatal diagnosis and prompt us to not uniformly dismiss tetraploidy as artifactual but to confirm it especially in cases with ultrasound abnormalities.