Transabdominal amnioinfusion in oligohydramnios at term before induction of labor with intact membranes: a randomized clinical trial.

Objective: Our purpose was to determine the effectiveness of transabdominal amnioinfusion before induction of labor in reducing the incidence of fetal distress in pregnancies with oligohydramnios at term.

Study Design: Between June 1991 and September 1994 primiparous women with ultrasonographic evidence of oligohydramnios at term, intact membranes, and unripe cervix (Bishop score < or = 6), candidates for induction of labor with cervical or vaginal prostaglandin E2 gel, were randomly selected to receive transabdominal amnioinfusion (amnioinfused group, n = 39) or to proceed with direct labor induction (control group, n = 40). Inclusion criteria were (1) singleton gestation, (2) vertex presentation, (3) ultrasonographic estimation of fetal weight > or = 2500 gm, and (4) reactive nonstress test. Fetoneonatal outcome variables were compared between the two groups. Statistical analysis used contingency tables, Student t test, or Wilcoxon rank-sum tests, where applicable.

Results: Amnioinfusion was successfully performed in 100% of the patients randomized for the procedure. The incidence of severely abnormal fetal heart rate tracings was significantly higher in the control than in the amnioinfused group (42% [17/33] vs 5% [2/37], relative risk 12.9, 95% confidence interval 2.4 to 56.4). The rate of cesarean sections performed for fetal distress was fivefold higher in the control group (25% [10/40] vs 5% [2/39], relative risk 4.9, 95% confidence interval 1.1 to 32.4). No bleeding complications or fetomaternal infectious morbidity were noticed.

Conclusion: Transabdominal amnioinfusion is a safe, effective option for the prevention of fetal distress in pregnancies with oligohydramnios at term with intact membranes and unripe cervix.