(1031) Premature rupture of membranes after serial amnioinfusions in fetuses with anhydramnios due to renal agenesis/dysplasia

To estimate the frequency of preterm premature rupture of membranes (PPROM) in fetuses with anhydramnios managed with serial amnioinfusions (AIs).

Study Design: Nineteen fetuses with anyhydramnios due to dysplastic kidneys or bilateral renal agenesis were treated in utero with serial AIs to prevent lung hypoplasia and Potter sequence. Fetuses with associated structural or chromosomal anomalies were not included. The first AI was performed for detailed anatomic evaluation; the amount of fluid infused targeted an amniotic fluid index (AFI) of 15-20 cm. Subsequent AIs were performed when AFI was between 5-8 cm. The initial goal was to reach 32 weeks of gestation. Patients with PPROM were managed expectantly until 32 weeks or until labor, fetal distress, or signs of clinical chorioamnionitis were noted.

Results:

279 AIs in 19 fetuses were performed (median n=15, range 3-22). Median gestational age (GA) at first AI was 22 weeks (range 17-25) and at last AI was 33 weeks (range 26-35). Four patients (21%) had PPROM: two at 26 weeks, one at 28 weeks, and one at 29 weeks. Seventeen of 19 cases reached at least 28 weeks, and 15/19 reached at least 30 weeks of gestation without PPROM. Fig1 shows the percentage of fetuses without PPROM after each AI. All cases underwent at least two AIs without PPROM; 95.4% underwent 3 to 9 AIs without PPROM. After the 10^th AI, the prevalence of PPROM increased by 4.5% for every two additional AI; 77.3% of subjects who underwent 16 or more AIs did not have PPROM. No women < 26 weeks of gestation had PPROM despite some having up to 6 AIs before that GA.

Conclusion: The risk of PPROM < 32 weeks of gestation after serial AIs is approximately 20%. The risk increases after 10 AIs or after 26 weeks of gestation, whichever comes first.