The detection rate for critical CHD was higher than for major defects. However, most of the defects missed by screening were noncritical lesions, eg, ventricular septal defects.
The authors estimated that in a population of 100,000 newborns, about 120 would have critical CHD, and 90 of those 120 cases would be detected by pulse oximetry. There would be 843 false positives (although 229 of the infants with false-positive results would have other noncardiac conditions). It would be necessary to perform 10.4 echocardiograms to detect one patient with critical CHD.
WHAT’S NEW: A stronger case for newborn pulse oximetry screening
Pulse oximetry prior to discharge from the newborn nursery is not performed routinely in all institutions. And even when screening is done, there may not be a protocol addressing abnormal results. Pulse oximetry is a safe, noninvasive, inexpensive, and reasonably sensitive test that will detect many cases of critical CHD, some of which will not be diagnosed antenatally. Earlier diagnosis of CHD may lead to earlier interventions and improved patient outcomes.
CAVEATS: Timing of screening may alter results
This trial was a cohort study, not a randomized controlled trial (RCT)—the gold standard method of validating a screening test. It is unlikely, however, that an RCT will ever be done.
Screening occurred within the first 24 hours; other investigators have screened >24 hours (up to 38 hours), which may have better results. The critical lesions most likely to be missed by pulse oximetry screening were those causing obstruction to the aortic arch,1 a finding that was also seen in other studies.5,7
TABLE
Screening newborns for congenital heart defects: The protocol1
| Pulse oximetry outcome* | Physical exam outcome | Next step |
|---|---|---|
| Normal | Normal | No further action |
| Abnormal | Normal | Repeat pulse oximetry in 2 h:
|
| Abnormal | Abnormal | echocardiogram |
| *Test is normal if pulse oximetry >95% on right hand and difference between the right hand and either foot is <2%. | ||
CHALLENGES TO IMPLEMENTATION: Early discharge, lack of equipment may interfere
Determining the timing of pulse oximetry screening is important. That’s particularly true because early discharge is a common practice, and early screening may increase the number of false-positive results. As a screening tool, pulse oximetry is inexpensive, and follow-up echocardiography—which is needed to exclude serious cases of CHD in patients with positive pulse oximetry—is noninvasive and relatively inexpensive. Echocardiography is not readily available in all communities, however, and transportation to a facility that offers this test would likely increase the cost of screening.
Acknowledgement
The PURLs Surveillance System is supported in part by Grant Number UL1RR024999 from the National Center for Research Resources, a Clinical Translational Science Award to the University of Chicago. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health.