Karyotypic abnormalities and hydramnios. Role of amniocentesis.

Hydramnios complicates up to 1.6% of pregnancies, with major fetal malformations found in an average of 20% of patients with hydramnios. Chromosomal abnormalities, although associated with some conditions in which hydramnios is present, have not been reported to complicate a significant percentage of hydramnios cases. Data from 45 patients admitted during the period January 1, 1985-May 31, 1990, were analyzed. All patients had hydramnios sufficiently severe to merit hospitalization for diagnosis and/or treatment. Amniocentesis was performed at the discretion of the attending physician and not under a specific protocol. The incidence of major fetal structural malformations was 36%. Of patients in whom amniocentesis was performed, 22% were found to have karyotypic abnormalities, none of which was specifically suspected prior to the amniocenteses. Neither the estimated gestational age nor the assessment of the amount of amniotic fluid differed between those with karyotypic abnormalities and those with normal chromosome complements. This information suggests that both advanced ultrasound studies and amniocentesis are beneficial in the evaluation of hydramnios.