To define clinically the initial (<24 hour) hemodynamic phenotypes (no/mild pulmonary hypertension [PH], precapillary PH, and postcapillary PH) in neonates with congenital diaphragmatic hernia (CDH) by echocardiography, and to assess their relationship with clinical outcomes.

This was a retrospective, single-center, observational study that included all neonates with CDH with an echocardiogram in the first 24 hours from 2018 to 2025. Phenotypes were categorized via an a priori -defined algorithm, characterized by clinical and echocardiography indices and were evaluated for association with mortality, need for extracorporeal life support, and key clinical outcomes.

Despite bidirectional atrial and/or ductal shunts in every echocardiogram (n = 28), phenotype identification was feasible with 2 (7%) no/mild PH, 18 (64%) precapillary PH, and 8 (29%) postcapillary PH phenotype. There was no association between phenotype and mortality or extracorporeal life support; however, the postcapillary phenotype was associated with earlier mortality, decreased surgical repair, and mortality when exposed to inhaled nitric oxide.

An algorithmic approach that includes early echocardiography can reliably identify hemodynamic phenotypes even in the presence of bidirectional shunts. Phenotypes may have distinct clinical trajectories in neonates with CDH.