Neonatal screening for critical congenital heart defects in a high prenatal detection region: Clinical performance and care pathways in the OXYNAT study

Pulse oximetry (PO) is increasingly used for neonatal screening of critical congenital heart defects (CCHDs), but its added value in regions with high prenatal detection rates remains unclear. To assess the diagnostic performance of PO alone and combined with clinical examination, and to evaluate post-screening care pathways in a large French regional network. The OXYNAT study is a population-based prospective cohort conducted in 28 maternity units in Nouvelle-Aquitaine (France) over 8 months (2018–2019). All asymptomatic newborns ≥ 35 weeks were screened by PO and/or clinical exam before discharge. CCHD cases were identified through an active multisource surveillance system and followed up for one year. Among 19,639 newborns included, PO screening alone showed a sensitivity of 52.9% and specificity of 97.8%. The combined strategy (PO + clinical examination) significantly improved sensitivity to 92.9%, with a specificity of 97.5%. Thirteen cases of CCHD were diagnosed; only 4 followed an optimal care pathway. Nine experienced delays due to incomplete clinical evaluations, misinterpretation of echocardiography, or underestimated symptoms. In some cases, associated conditions (e.g. anal atresia) masked cardiac signs and contributed to late diagnosis. Even in regions with strong prenatal screening programs, neonatal PO screening remains valuable when combined with systematic clinical assessment. Our findings highlight the importance of timely clinical follow-up, pediatric echocardiographic expertise, and integrated referral pathways to avoid delayed care in infants with CCHDs.