Prenatally Diagnosed Large Lung Lesions: Timing of Resection and Perinatal Outcomes

Introduction: Fetuses with large lung lesions including congenital cystic adenomatoid malformations (CCAMs) are at risk for cardiopulmonary compromise. Prenatal maternal betamethasone and cyst drainage for micro- and macrocystic lesions respectively have improved outcomes yet some lesions remain large and require resection before birth (open fetal surgery, OFS), at delivery via an Ex Utero Intrapartum Treatment (EXIT), or immediately post cesarean section (section-to-resection, STR). We sought to compare prenatal characteristics and outcomes in fetuses undergoing OFS, EXIT, or STR to inform decision-making and prenatal counseling. Methods: A single institution retrospective review was conducted evaluating patients undergoing OFS, EXIT, or STR for prenatally diagnosed lung lesions from 2000 to 2021. Specimens were reviewed by an anatomic pathologist. Lesions were divided into “CCAMs” (the largest pathology group) and “all lung lesions” since pathologic diagnosis is not possible during prenatal evaluation when care decisions are made. Prenatal variables included initial, greatest, and final CCAM volume-ratio (CVR), betamethasone use/frequency, cyst drainage, and the presence of hydrops. Outcomes included survival, ECMO utilization, NICU length of stay (LOS), postnatal nitric oxide use, and ventilator days. Results: Sixty-nine percent (59 of 85 patients) of lung lesions undergoing resection were CCAMs. Among patients with pathologic diagnosis of CCAM, the initial, largest, and final CVRs were greatest in OFS followed by EXIT and STR patients. Similarly, the incidence of hydrops was significantly greater and the rate of hydrops resolution was lower in the OFS group. Although the rate of cyst drainage did not differ between groups, maternal betamethasone use varied significantly (OFS 60.0%, EXIT 100.0%, STR 74.3%; p = 0.0378). Notably, all OFS took place prior to 2014. There was no difference in survival, ventilator days, nitric oxide, NICU LOS, or ECMO between groups. In multiple variable logistic modeling, determinants of survival to NICU discharge among patients undergoing resection with a pathologic diagnosis of CCAM included initial CVR <3.5 and need for <3 maternal betamethasone doses. Conclusion: For CCAMs that remain large despite maternal betamethasone or cyst drainage, surgical resection via OFS, EXIT, or STR are viable options with favorable and comparable survival between groups. In the modern era there has been a shift from OFS and EXIT procedures to STR for fetuses with persistently large lung lesions. This shift has been fueled by the increased use of maternal betamethasone and introduction of a Special Delivery Unit during the study period and the appreciation of similar fetal and neonatal outcomes for STR vs. EXIT and OFS with reduced maternal morbidity associated with a STR. Accordingly, efforts to optimize multidisciplinary perinatal care for fetuses with large lung lesions are important to inform patient selection criteria and promote STR as the preferred surgical approach in the modern era. Level of Evidence: Level IV.