OBJECTIVE: To determine if timing of first postnatal echocardiogram (ECHO), early vs delayed, affects the use of extracorporeal membrane oxygenation (ECMO) and survival to discharge in neonates with congenital diaphragmatic hernia (CDH). STUDY DESIGN: We retrospectively reviewed 306 neonates with CDH managed between January 2007 through December 2023. We excluded 21 neonates diagnosed at >
24 hours age and 14 outborn neonates transferred at >
12 hours age. Based on initial ECHO guideline recommendation changes, we compared 2 ECHO cohorts: early (<
24 hours, 2007-2015) vs delayed (>
24 hours, 2016-2023). Outcomes of interest included ECMO use, survival, rates of cardiopulmonary therapies, and key ECHO parameters. RESULTS: The median age for first preoperative ECHO was 7 hours (IQR, 4-13 hours) in the early epoch vs 40 hours (IQR, 19-62 hours) in the delayed epoch (P <
.001). Despite similar demographics including gestation, birth weight, defect size, and intrathoracic liver, ECMO use (31% vs 9%) and survival (70% vs 82%) were improved significantly in association with delayed timing of first ECHO (P <
.05). Measures of pulmonary hypertension, ventricular size, and ventricular function were similar, but significantly less inhaled nitrous oxide and vasoactive drugs were used in the delayed ECHO epoch. CONCLUSIONS: A delay in the timing of the initial postnatal ECHO for critically ill neonates with CDH, as part of a broader series of guideline changes, was associated with less ECMO, improved survival, and lower use of inhaled nitrous oxide and vasoactive drugs despite similar ECHO measures of pulmonary hypertension, ventricular size, and ventricular function. Randomized studies are needed to define better the optimal timing and interventions related to the initial ECHO for CDH.