Ultrasound placental cysts associated with massive placental stem villous hydrops, diploid DNA content, and exomphalos.

A pregnancy associated with antenatally detected placental cysts and an anterior abdominal wall defect is described. The anterior abdominal wall defect proved to be an exomphalos in which a short segment of normal cord intervened between the herniated sac and the cord insertion. The placental cysts detected antenatally by ultrasound were shown subsequently to be massive main stem villous hydrops with cisternal formation but no evidence of trophoblastic hyperplasia. Antenatal placental biopsy and amniocentesis revealed a normal male karyotype. Confined placental mosaicism for triploidy was excluded by DNA flow cytometry. This case was not associated with Beckwith-Wiedemann syndrome.