Premature rupture of membranes after serial amnioinfusions in fetuses with early anhydramnios due to severe renal disease/lower urinary obstruction.

Aim: This study estimates the frequency of preterm premature rupture of membranes (PPROM) in fetuses with early anhydramnios due to severe renal or urinary disease treated with serial amnioinfusions (AIs).

Methods: Fetuses diagnosed with early anhydramnios (<25 weeks gestation) secondary to severe renal disease or urinary tract obstruction underwent serial AIs at two centers, to reduce uterine compression and prevent pulmonary hypoplasia. Fetuses with structural or chromosomal anomalies were excluded. AIs were performed to maintain an amniotic fluid index (AFI) of 15-20 cm. Patients were monitored biweekly, and AIs were repeated whenever AFI decreased to 5-8 cm. Signs of fetal distress, membrane detachment, and clinical chorioamnionitis were closely monitored. PPROM was defined as spontaneous membrane rupture before 35 weeks gestation, or delivery. The frequency of PPROM was analyzed in relation to gestational age at diagnosis, and to the number of AIs performed. Associations between the number of AIs and PPROM were evaluated with logistic regression analysis.

Results: A total of 340 AIs were performed in 32 fetuses between 19 and 35 weeks gestation with a median (range) of 13 (2-22) AIs per patient. PPROM occurred in 12 patients (37.5%), with seven cases (21.8%) occurring before 32 weeks. PPROM occurred in 30.8% (4/13) of cases with 2-9 AIs and in 42.1% (8/19) of cases with 10-22 AIs (OR 1.6 [95% CI 0.36-7.25; p=0.51]). Twenty (62.5%) cases reached 35 weeks or delivery without PPROM. Notably, 28/32 patients (87.5%) completed 9 AIs without presenting PPROM. No PPROM occurred before 26 weeks.

Conclusion: The overall risk of PPROM <35 weeks following serial AIs for early anhydramnios due to severe renal or urinary tract disease was 37.5%. Despite no significant differences in PPROM related to the number of AIs, there is an increment in PPROM frequency after nine AIs.