Role of amnioinfusion in the management of premature rupture of the membranes at < 26 weeks' gestation

OBJECTIVE: We sought to evaluate whether serial amnioinfusions for persistent oligohydramnios can affect the perinatal and long-term outcomes in extreme cases of preterm premature rupture of membranes. STUDY DESIGN: All singleton pregnancies with preterm premature rupture of membranes at <26 weeks' gestation and lasting >4 days between January 1991 and June 1998 were included. Amniotic fluid volume was assessed as the maximum cord-free pocket with serial ultrasonographic examinations. Consenting women with persistent (>4 days) oligohydramnios (amniotic fluid less than or equal to2 cm) received serial transabdominal amnioinfusions to maintain an amniotic fluid pocket >2 cm. The pregnancy, neonatal, and long-term neurologic outcomes of the cases that spontaneously maintained a median amniotic fluid pocket >2 cm (amnioinfusion-not-necessary group) were compared with those of women with oligohydramnios who underwent amnioinfusion but continued to have a median amniotic fluid pocket after preterm premature rupture of membranes less than or equal to2 cm (persistent oligohydramnios group) and with those of women in whom oligohydramnios was alleviated by the procedure for at least 48 hours (successful amnioinfusion group). Statistical analysis included the Wilcoxon rank-sum test and the Fisher exact test, with a 2-tailed P < .05 considered significant, RESULTS: Among the 49 women included in the study, 13(26.5%) did not have oligohydramnios, the neonatal survival rate was 92%, and normal fetal lung development and neurologic outcome were achieved in all survivors. The remaining 36 women had oligohydramnios, and all underwent serial amnioinfusions, which successfully restored a median amniotic fluid pocket >2 cm for greater than or equal to 48 hours in 11 (30%) patients. This successful amnioinfusion group was comparable with the persistent oligohydramnios group (n = 25) in gestational age at first amnioinfusion (median, 20.2 weeks; range, 16-25.6 weeks; vs median, 20.3 weeks; range, 16.5-24.2 weeks; P = .4), number of amnioinfusions (median, 3; range, 1-9, vs median, 3; range, 1-5; P = .4), and interval between amnioinfusions (median, 6 days; range, 4-14 days; vs median, 8 days; range, 6-43 days; P = .1). However, patients in the persistent oligohydramnios group had a significantly shorter interval to delivery, tower neonatal survival (20%), and higher rates of pulmonary hypoplasia (62%) and abnormal neurologic outcomes (60%) than the patients in the groups in which amnioinfusion was not necessary or was successful (all P less than or equal to .01). CONCLUSION: Pregnancies with preterm premature rupture of membranes-related oligohydramnios at <26 weeks' gestation in which serial amnioinfusions successfully alleviate oligohydramnios have a perinatal outcome that is significantly better than the outcome in those with persistent oligohydramnios and is comparable with gestations with preterm premature rupture of membranes in which oligohydramnios never develops.