Premature rupture of the membranes between 20 and 25 weeks' gestation: role of amniotic fluid volume in perinatal outcome.

OBJECTIVE

Our purpose was to prospectively study the relationship between amniotic fluid volume and perinatal outcome in pregnancies complicated by premature rupture of the membranes before fetal viability.

STUDY DESIGN

The study population consisted of 178 singleton pregnancies with premature rupture of membranes between 20 and 25 weeks' gestation who were managed expectantly. Serial amniotic fluid volume measurements were made and their relationship to the neonatal survival rate, incidence of chorioamnionitis, and other perinatal outcomes was determined.

RESULTS

Seventy-four patients were delivered before 25 weeks of gestation and only five infants (6.7%) survived. In contrast, 104 patients were delivered between 26 and 34 weeks, and 93 infants (89.4%) survived (p < 0.001). There were 107 pregnancies with adequate amniotic fluid volume after premature rupture of membranes on admission. Of these 16 patients were delivered before 25 weeks of gestation, and the remaining 91 patients were able to carry their pregnancies beyond 25 weeks of gestation. This was significantly different from 71 patients who demonstrated inadequate amniotic fluid volume on admission to the hospital, of whom 58 were delivered before 25 weeks and only 13 continued the pregnancy beyond 25 weeks (p < 0.05). At gestations between 26 and 34 weeks chorioamnionitis occurred in 22 of 91 (24.1%) patients with adequate amniotic fluid volume versus nine of 13 patients (69.2%) with inadequate amniotic fluid volume (p < 0.001). The incidence of perinatal death for pregnancies between 26 and 34 weeks with adequate versus inadequate amniotic fluid volume was 2.1% and 69.2%, respectively (p > 0.001). Overall survival rate and incidence of chorioamnionitis were 55% and 26.4%, respectively.

CONCLUSIONS

Delivery of pregnancies between 20 and 25 weeks of gestation with premature rupture of membranes carries very high risk of neonatal mortality. The results of this study suggest that women with adequate amniotic fluid volume have a better chance to continue their pregnancy beyond 25 weeks of gestation and have a higher neonatal survival rate than those with inadequate amniotic fluid volume. The incidence of perinatal death and chorioamnionitis in patients who carry a pregnancy beyond 25 weeks is correlated with inadequate amniotic fluid volume.