Prenatal Prognosis of Omphalocele Using Magnetic Resonance Imaging Measurement of Fetal Lung Volumes.

Background: Omphalocele is a congenital midline abdominal wall defect resulting in herniation of viscera into a membrane-covered sac. Pulmonary complications, including pulmonary hypoplasia, pulmonary hypertension, and prolonged respiratory support are a leading cause of neonatal morbidity and mortality.

Objective(s): This study aimed to assess the role of fetal MRI-derived lung volumes and omphalocele defect size as clinical tools to prognosticate postnatal pulmonary morbidity and neonatal mortality in those with a prenatally diagnosed omphalocele (PDO).

Study Design: This was a retrospective cohort study of all pregnancies with PDO at our fetal center from 2007-2023. Pregnancies with aneuploidy or concurrent life-limiting fetal anomalies were excluded. Using fetal MRI, observed-to-expected total fetal lung volume (O/E TLV) ratios were determined by a previously published method. The transverse diameter of the abdominal defect was also measured. The O/E TLV ratios and abdominal defect measurements were compared with postnatal outcomes. The primary outcome was death at any time. Secondary outcomes included death in the first 30 days of life or before discharge from birth hospitalization, the requirement of respiratory support with intubation and mechanical ventilation, or development of pulmonary hypertension.

Results: Of 101 pregnancies with a PDO, 54 pregnancies (53.5%) with prenatally diagnosed omphalocele met inclusion criteria. There was a significant increase in the rate of death when compared between the three O/E TLV classifications: 1/36 (2.8%) in the O/E≥50% group, 3/14 (21.4%) in the O/E 25%-49.9% group, and 4/4 (100%) in the O/E<25% group (P<.001). The rate of intubation increased with the severity of O/E TLV classification, with 27.8% in the O/E≥50% group, 64.3% in the O/E 25%-49.9% group, and 100% in the O/E<25% group (P=.003). The rate of pulmonary hypertension was also higher in the O/E 25%-49.9% (50.0%) and the O/E<25% (50.0%) groups compared to the O/E≥50% group (8.3%, P=.002). There was no association between the transverse diameter of the abdominal wall defect and the primary outcome of death (OR=1.08 95% CI=[0.65-1.78], P=.77).

Conclusions: In our cohort of patients with PDO, O/E TLV<50% is associated with death, need for intubation, prolonged intubation, and pulmonary hypertension. In contrast, omphalocele size demonstrated no prognostic value for these outcomes. The strong association between low fetal lung volume on MRI and poor neonatal outcomes highlights the utility of fetal MRI for estimating postnatal prognosis. Clinicians can utilize fetal lung volumes to direct perinatal counseling and optimize the plan of care.