Evidence for CCHD screening and its practical application using pulse oximetry.

Pulse oximetry screening is a highly specific, moderately sensitive test for detecting critical congenital heart defects (CCHDs) that meets the criteria for universal screening. The possibility of using pulse oximetry as a screening test was first investigated over 10 years ago and since then data from more than 370,000 screened babies have now been published. There is significant heterogeneity in published screening protocols but almost all demonstrate that the addition of pulse oximetry screening reduces the 'diagnostic gap' - i.e. those babies with CCHD who are missed by existing screening methods and discharged from hospital before the diagnosis has been established. This review considers the available evidence and assesses the practical options for the introduction of pulse oximetry screening.