Perinatal outcome following conservative management of mid-trimester pre-labour rupture of the membranes.

OBJECTIVE: To assess perinatal outcome and the effect of antenatal steroid use following conservative management of 86 consecutive singleton pregnancies complicated by pre-labour rupture of membranes (ROM) in the mid-trimester (13-26 weeks; mean 22.8 weeks).

METHODOLOGY: Review of obstetric and neonatal case notes between 1 January 1990 and 31 December 1993.

RESULTS: The duration of ruptured membranes (latent period) ranged from 1.25 to 105 days (mean 23.8 days; median 14 days) and was inversely related to gestational age at ROM. There was clinical evidence of chorioamnionitis in 39.5% with placental histological changes consistent with chorioamnionitis in 76.6%. All infants were delivered before 33 weeks gestation (mean 26 weeks). Overall, the mortality rate was 43.0% but 62.5% in infants with ROM before 24 completed weeks gestation. Adverse outcome (defined as death, severe intraventricular haemorrhage (IVH) or periventricular leucomalacia (PVL)) occurred in 46.5% and was significantly related to both gestation at delivery and gestation at ROM. In the group (n = 40) with ROM before 24 weeks gestation, adverse outcome occurred in 65% and was inversely related to gestation at ROM independent of gestation at delivery. Antenatal steroid administration resulted in less adverse outcome independent of gestation at delivery (OR 0.31; 95% CI (0.09-0.98; P = 0.046)).

CONCLUSION: From the neonatal perspective conservative management is justified for pregnancies with ROM at or after 24 weeks gestation; in this group the use of antenatal steroids prior to delivery may improve perinatal outcome. A poor outcome is associated with ROM that occurs before 24 weeks gestation.