Fetal Lung Volume Measurement via MRI Helps Predict Giant Omphalocele Complications

Research study background

A giant omphalocele (GO) is a rare congenital defect of the abdominal wall measuring 5 cm or larger that causes a large portion of the liver to protrude outside the body of a developing fetus. GO poses a higher risk of pulmonary morbidity, including the need for supplemental oxygen, prolonged ventilation and tracheostomy. Earlier studies of prenatal predictors of survival for GO included fetal ultrasound for measuring lung/thorax ratio and chest/trunk ratio and fetal MRI for calculating total lung volume (TLV). While previous research described generalized complications related to GO, it didn’t focus on pulmonary issues. At many institutions, prenatal management of GO focuses on preparation for delivery with routine fetal ultrasounds. The Colorado Fetal Care Center at Children’s Hospital Colorado routinely uses fetal MRI to monitor these pregnancies. It’s the standard of care to obtain TLV and observed‐to‐expected TLV (O/E TLV) for all omphalocele diagnoses.

In this study, investigators conducted a 10-year retrospective review of 26 GO pregnancies managed at Children’s Colorado between 2012 and 2021 that met strict inclusion criteria. They hypothesized that prenatal MRI measurements of TLV and observed‐to‐expected TLV (O/E TLV) ratios would correlate with postnatal pulmonary morbidity, including delivery room intubation and tracheostomy. The overall analysis found that 50% of patients had pulmonary hypertension (mostly mild) and 69% required intubation (31% while in the delivery room). The overall survival rate was 85%. Among those who did not survive, 75% required intubation in the delivery room.

To assess for predictors of postnatal pulmonary outcomes, the team calculated fetal MRI TLV between 32 and 36 weeks gestation and observed-to-expected (O/E) TLV throughout the pregnancy. In the MRIs between 32 and 36 weeks, those needing delivery room intubation had significantly lower fetal TLV, and all with TLV under 35 mL required a tracheostomy. When researchers used O/E TLV to analyze the entire cohort, it correlated with the need for delivery room intubation and predicted both survival and the need for tracheostomy.

Clinical implications

This study demonstrated that fetal MRI, specifically O/E TLV, can help predict acute respiratory needs at the time of delivery, informing prenatal counseling and delivery planning. Many patients travel long distances to the Colorado Fetal Care Center, where the team is already using this data to advise families on whether they can safely return home for delivery.

Additionally, because the surgical approach to GO varies widely across institutions, the authors suggest that using fetal TLV to predict the severity of pulmonary hypoplasia could help assess which patients are best suited for early closure techniques and which should have a delayed repair strategy.