EP10.21: Changes in lung size/volume and intrapulmonary Doppler velocimetry in fetuses with anhydramnios treated with serial amnioinfusions

To evaluate changes in fetal lung size/volume and intrapulmonary circulation after serial amnioinfusions (AI) in fetuses diagnosed with anhydramnios prior to 22 weeks of gestation. Nine fetuses with anhydramnios due to renal agenesis (n = 4) or renal dysplasia (n = 5) were treated with serial AI aiming to maintain an AFI of 15-17 cm. until 32 weeks or PPROM. Before AI, the following parameters were obtained: fetal lung area, total lung volume (TLV), observed/expected lung-to-head ratio (O/E LHR), thorax circumference, cardiothoracic ratio (CTR), and Doppler velocimetry of the main intrapulmonary artery (IP). Longitudinal changes in fetal lung biometrics, and differences between first and last AI are reported. A total of 126 (median n = 14 [7-22] per case) AIs were performed. PPROM occurred in 2 cases at 28 and 29 weeks, respectively, and in 5 after 30 weeks of gestation. Two fetuses reached delivery without PPROM. All fetuses were delivered ≥29+6 weeks/days of gestation. From the first to the last AI, there was an increase in left lung area (z-score [z-sc] -1.86 [0.35] vs. -0.35 [0.56]; p < 0.001), right lung area (z-sc -2.09 [0.64] vs. -0.81 [0.8]; p < 0.001), left O/E LHR (56.6% [21.9] vs. 73.3% [9.8]; p = 0.05), and right O/E LHR (57.4% [12.2] vs. 73.4% [10.5]; p = 0.009). TLV increased, but differences were not significant (z-sc -0.24 [1.08] vs. 0.53 [1.75]; p = 0.7). No differences in thoracic circumference (z-sc -0.57 [0.7] vs. -0.56 [0.54]; p = 0.97) or CTR (0.58 [0.05] vs. 0.58 [0.06]; p = 1) were documented. The distribution of all lung biometric parameters across pregnancy consistently showed values below the expected mean for gestational age. IP-pulsatility index (PI) decreased from the first (mean [sd] 3.6 [0.65]) to the last AI (3.0 [0.46]; p = 0.02) with normally distributed values thereafter. In fetuses with chronic anhydramnios, despite increases in lung size after serial AIs and normalization of the IP circulation, lung measurements were below the expected mean for gestational age.