Objective: To evaluate whether successful amnioinfusion is an independent predictor of perinatal survival in a cohort of cases with extreme and persistent oligohydramnios due to preterm premature rupture of membranes (pPROM) who reached viability and were managed with serial amnioinfusions.
Study design: We included all consecutive singleton pregnancies with pPROM at <26 weeks and oligohydramnios lasting >4 days between 1/1991 and 12/2001 and who consented to undergo amnioinfusion (n=77). Women received serial transabdominal amnioinfusions in an attempt to maintain a pocket of fluid >2 cm. The procedure was deemed successful if the median deepest pocket of fluid during the latency period was >2 cm. Excluded were miscarriages (n=10), fetal deaths before viability (24 weeks) (n=15), and cases that did not develop oligohydramnios (n=17). Prenatal predictors of outcome were compared between cases who survived the perinatal period and those who did not using Wilcoxon rank-sum test, Fisher's exact test and stepwise logistic regression analysis, with a two-tailed P<0.05 considered significant.
Results: Of the 35 patients fulfilling the study criteria, 20 (57%) survived the perinatal period. Perinatal survivors had similar gestational age at pPROM (P=0.68) and at first amnioinfusion (P=0.53) as those who died in the perinatal period, but longer latency (P=0.013). Consequently, median gestational age at delivery [29.2 (25.4-35.3) weeks versus 26.1 (24.0-34.0) weeks, P<0.001] and median birth weight [1220 (650-2240) g versus 863 (520-2200) g, P=0.001] were significantly greater among survivors than among those who died. Significant predictors of survival at univariate analysis were entered into a stepwise logistic regression analysis in the chronological order in which they normally occur. The analysis demonstrated that successful amnioinfusion (OR=6.9, 95% CI 1.2-40.4) and administration of steroids (OR=14.6, 95% CI 1.5-144.1) were independent and significant predictors of perinatal survival.
Conclusion: In a cohort of women with pPROM at <26 weeks and severe oligohydramnios managed with serial amnioinfusions, successful procedures and prenatal administration of corticosteroids are the only independent predictors of perinatal survival.