Background Pulse oximetry (POX) is gaining ground as a screening test for severe congenital heart disease (CHDs) but its sensitivity towards aortic coarctation is low. Pulse oximetry-derived perfusion index (PI) has been proposed as a tool to detect critical left heart obstruction but has never been studied prospectively.

Aim To evaluate the efficacy of a neonatal screening combining PI and POX in a large population and to assess the impact of the test in hospitals with different level of care.

Methods Collaborative prospective study in 16 Italian hospitals. Asymptomatic infants who had not received prior cardiac evaluation were tested before discharge (48–72HoL) for pre-and post-ductal SpO₂ and PI. Cut off: SpO₂ 3%, PI

Results 50244 infants were born during the study period (76.7% in tertiary hospitals). 180 CHDs were detected before screening (142 antenatally, 38 clinically). 42169 newborns were screened. 3 CHDs were identified (2 for low SpO₂, 1 coarctation for low PI). 4 cases (2 coarctations) were missed. False positive rate was 0,45% (0,27% for PI). While in tertiary hospitals 95% of CHDs were identified before screening, in 1°-2° level units only 28% were detected clinically and PI-POX screening added a 46% sensitivity to the sole physical examination.

Conclusion Pre-discharge PI-POX screening provides a significant benefit only in 1°-2° level hospitals, where the rate of clinical recognition is low.

PI is capable to identify cases of aortic coarctation that POX misses but needs further evaluation in populations with a higher rate of missed diagnoses.