O2160: Fetal Ultrasound and MRI Discordance in Predicting Outcomes Associated with Congenital Diaphragmatic Hernia

Background: Prenatal ultrasound (U/S) and MRI are complementary imaging modalities used to evaluate and predict outcomes in pregnancies complicated by congenital diaphragmatic hernia (CDH). At many institutions, disease severity guides mode of delivery (vaginal vs cesarian delivery) and initial resuscitation with many centers favoring cesarian birth with ECMO on standby for severe case. A clinical quandary arises when one prenatal imaging modality suggests a moderate case and the other suggests a severe case. Thus, the primary objective of this study was to determine whether prenatal U/S or MRI more accurately predicts outcomes when imaging is discordant.

Methods: We performed a retrospective review of all severe CDH cases between 2012 and 2023 at our institution. We defined severe cases by either an observed to expected lung-head-ratio (O/E LHR) of < 35% with liver herniation measured by U/S or a percent predicted lung volume (PPLV) < 15% measured by MRI. MRI discordance was defined by an MRI suggestive of a severe case and an U/S suggestive of a moderate case, and U/S discordance was defined as the converse. The primary outcome measure was rate of ECMO cannulation with secondary outcomes including number of days on ECMO, length of hospitalization, and survival to discharge. Univariate analysis was performed using fisher exact test for categorical variables and Kruskal-Wallis test for continuous variables.

Results: Among the 120 CDH cases managed during the study period, 37 (31%) were defined as severe. Of these, 18 (49%) were discordant with a majority (n=12) identified as MRI discordant (Table 1). Among the MRI discordant group, ECMO was required in 92% of cases compared to just 33% of the U/S discordant group (p=0.022). Given the low incidence of neonates in the U/S discordant group require ECMO (n=2), there were no significant differences in time on ECMO between groups. Although it did not reach statistical significance, survival to hospital discharge among MRI discordant cases was half of that compared to the ultrasound discordant group (42% vs 83%, p=0.152, Table 2).

Conclusion: In nearly half of severe CDH cases, fetal ultrasound and MRI are discordant. This analysis, suggests that in the setting of discordance PPLV < 15% on MRI is more predictive of severe cases of CDH and need for ECMO than an ultrasound O/E LHR < 35% with liver herniation. When discordant, fetal MRI should be utilized to predict severe cases of CDH and guide antenatal care and delivery planning.