New Anhydramnios after 22 Weeks and Pulmonary Hypoplasia

Introduction: Anhydramnios due to renal failure prior to 22 weeks of gestational age (WGA) is associated with lethal pulmonary hypoplasia but after 22 WGA outcomes are less clear. We evaluated whether these fetuses, with new anhydramnios after 22 WGA, incur significant risk of severe neonatal pulmonary morbidity.

This retrospective study of singleton pregnancies diagnosed with new-onset renal anhydramnios after 22 WGA following verifiable normal AFI on ultrasound before 22 WGA from 2021 to 2023. Cases with bilateral renal agenesis, premature rupture of membranes, and nonrenal malformations were excluded.

During the study period 53,698 s trimester ultrasound examinations were performed, of which 82 patients had new anhydramnios after 22 weeks, and 6 met criteria for inclusion in the study. Renal anhydramnios in each was secondary to a lower urinary tract outlet obstruction. Two of these (2/6, 33%) underwent procedures that corrected anhydramnios and survived, the rest suffered lethal pulmonary hypoplasia.

Onset of, and persistent, renal anhydramnios after 22 WGA is associated with lethal pulmonary morbidity. Although clinical trials to date have focused on intervention for patients with renal anhydramnios prior to 22 WGA, investigation of treatments those with renal anhydramnios after 22 WGA is warranted to mitigate severe pulmonary hypoplasia.