What is Known: • The addition of pulse oximetry (Pulsox) screening to the routine newborn examination increases the sensitivity of CCHD detection. Pulsox screening is also highly specific for CCHD in asymptomatic neonates, with low false-positive rates. • Early diagnosis of CCHD improves patient outcomes in relation to both morbidity and mortality.

What is New: • The proportion of affected infants with an abnormal Pulsox result varies by CCHD diagnosis and screening threshold. In our study using the ≤ 95% threshold gave the highest proportion of neonates with abnormal saturations at admission. • In general, Pulsox yield of abnormal results is low for CCHD diagnoses not associated with critically reduced pulmonary blood flow; however, increasing the Pulsox threshold increased the proportion of infants with an abnormal result.