Hazards of amniocentesis: an unidentifiable fragment.

A 38-year-old woman had amniocentesis performed for advanced maternal age. The karyotype of the cultured amniotic fluid cells showed a minute fragment in all cells analyzed, 47,XY+Fg. The fragment could not be identified. For medical reasons the pregnancy had to be terminated at 34 weeks. Both skin and blood cultures from the aborted fetus showed a 47,XY,21+ karyotype.