Abstract
<b><i>Introduction:</i></b> The optimal protocol for serial amnioinfusions to maintain amniotic fluid in pregnancies with early-onset fetal renal anhydramnios before 22 weeks is not known. We compared the performance of two different approaches. <b><i>Methods:</i></b> A secondary analysis was conducted of serial amnioinfusions performed by a single center during the external pilot and feasibility phases of the Renal Anhydramnios Fetal Therapy (RAFT) trial. During the external pilot, higher amnioinfusion volumes were given less frequently; in the feasibility study, smaller volume amnioinfusions were administered more frequently. Procedural details, complications, and obstetric outcomes were compared between the two groups using Pearson’s χ<sup>2</sup> or Fisher’s exact tests for categorical variables and Student’s <i>t</i> tests or Wilcoxon rank-sum tests for continuous variables. The adjusted association between procedural details and chorioamniotic separation was obtained through a multivariate repeated measure logistic regression model. <b><i>Results:</i></b> Eleven participants underwent 159 amnioinfusions (external pilot: 3 patients, 21 amnioinfusions; feasibility: 8 patients, 138 amnioinfusions). External pilot participants had fewer amnioinfusions (7 vs. 19.5 in the feasibility group, <i>p</i> = 0.04), larger amnioinfusion volume (750 vs. 500 mL, <i>p</i> < 0.01), and longer interval between amnioinfusions (6 [4–7] vs. 4 [3–5] days, <i>p</i> < 0.01). In the external pilot, chorioamniotic separation was more common (28.6% vs. 5.8%, <i>p</i> < 0.01), preterm prelabor rupture of membranes (PPROM) occurred sooner after amnioinfusion initiation (28 ± 21.5 vs. 75.6 ± 24.1 days, <i>p</i> = 0.03), and duration of maintained amniotic fluid between first and last amnioinfusion was shorter (38 ± 17.3 vs. 71 ± 19 days, <i>p</i> = 0.03), compared to the feasibility group. While delivery gestational age was similar (35.1 ± 1.7 vs. 33.8 ± 1.5 weeks, <i>p</i> = 0.21), feasibility participants maintained amniotic fluid longer. <b><i>Conclusion:</i></b> Small volume serial amnioinfusions performed more frequently maintain normal amniotic fluid volume longer because of delayed occurrence of PPROM.