Background: Identifying Critical Congenital Heart Disease (CCHD) before life-threatening symptoms remains a diagnostic challenge and public health priority. Newborn pulse oximetry screening (POS) to detect asymptomatic CCHD is the national standard of care since 2011. To improve POS efficiency and effectiveness, protocol changes were proposed in 2020: eliminating the third screen and requiring that both pre- and post-ductal saturations be ≥95% with a ≤3% difference. We describe a large contemporary cohort of infants born with CCHD in the Northwest United States whose diagnosis was unknown prior to POS.

Methods: Infants born between July 2015 and May 2022 who were postnatally diagnosed with CCHD by POS or signs/symptoms after screening and treated at one of two congenital cardiac surgical programs in Washington were included. Patients were identified using our registry of infants with CCHD. Medical records were reviewed for details about POS, CCHD diagnosis, medical transport, and outcomes.  

Results: Of the 648 infants with CCHD, 84 (13%) underwent POS which detected CCHD in 49 (58.3% true positives) and missed CCHD in 35 (41.7% false negatives). 68/84 (81%) underwent a single POS yielding an actionable result, 8 (9.5%) required a second for an indeterminate first screen, and 8 (9.5%) required three screens. 2/16 infants requiring multiple screens ultimately passed. Of 8 patients requiring a third screen, 5 had a prolonged time between the first and third screens (2:45 to 9:12 hours). Of 35 missed cases, 25 (71.4%) were discharged home prior to diagnosis with 8 (22.9%) re-presenting in shock. In contrast, 2/49 (4.1%) of cases identified by POS developed shock (p=0.01). Most infants identified by POS had total anomalous pulmonary venous return (12, 24.5%), but diagnoses spanned 14 diseases. Prior to transfer following failed POS, 41 (83.7%) had echocardiography performed, 33 (67.3%) had prostaglandin initiated, and 12 (24.5%) were intubated for transport. Coarctation accounted for most missed cases (20, 57.1%) and was more likely to have a false negative screen (p<0.005). POS values were available for 30/35 patients with false negative screens. Applying suggested modifications to the POS protocol would have recategorized 4 infants (11.4%) as true positives.   

Conclusion: In our CCHD registry, 13% of newborns underwent POS, with 7.6%, or approximately 7 infants/year, identified and transferred to a higher level of care. False negative POS remains a challenge resulting in a delayed diagnosis and raising the risk for shock. Changes to the POS criteria would have potentially identified an additional 4 infants. Few infants required two or three screens, with most ultimately failing. Adherence to the standard of repeat testing 1 hour after an indeterminate test was poor, delaying definitive disposition. Most infants with CCHD identified by POS were born in a regional hospital with echocardiography capability prior to transfer, transferred without complications, and remained asymptomatic. This study further corroborates the value of POS and supports modifications to the screening protocol to increase its efficiency and sensitivity.