Hydramnios prediction of adverse perinatal outcome.

OBJECTIVE

To determine whether hydramnios is associated with an increased risk of adverse perinatal outcomes.

METHODS

Computerized records of all ultrasound examinations done at the University of Alabama at Birmingham from 1986 to 1996 (n = 40,065) were reviewed to identify 370 women with singleton pregnancies beyond 20 weeks' gestation and hydramnios diagnosed sonographically by amniotic fluid index of 25 cm or more, largest vertical pocket of 8 cm or more, or subjective impression. Controls were all women with singleton gestations with normal amniotic fluid volumes (n = 36,426). Obstetric outcomes were determined by cross-reference to our database. Cases with hydramnios were compared with controls for perinatal death, anomaly rate, fetal growth restriction (FGR), cesarean delivery, fetal aneuploidy, and maternal diabetes. Cases were sorted according to diabetes status, after which perinatal death, anomaly rate, FGR, cesarean delivery, and fetal aneuploidy were compared again.

RESULTS

The incidence of hydramnios was 1%. The perinatal mortality rate in all women with hydramnios was 49 per 1000 births, compared with 14 per 1000 births in the control group (P < .001). Women with hydramnios had 25 times more anomalies than controls (8.4% versus 0.3%; P < .001), although the prevalence of fetal aneuploidy was not significantly different (one in 370 versus one in 3643; P = .10). The cesarean rate was three times higher in women with hydramnios compared with controls (47.0% versus 16.4%; P < .001). When hydramnios cases were divided according to diabetes status, all of the increased risk was in nondiabetic women: Perinatal mortality was 60 per 1000 in nondiabetic women versus 0 per 1000 in diabetic women (P = .03); the anomaly rate was 10.4% versus 0%, respectively (P = .005).

CONCLUSION

Hydramnios indicated an increased risk of adverse perinatal outcomes, especially if not associated with diabetes. A comprehensive fetal evaluation, a workup to rule out maternal factors, and fetal surveillance are warranted; amniocentesis for fetal karyotype analysis might not be necessary.