Newborn Screening

Newborn screening has been used for many conditions over the years.  Everyone is most familiar with the newborn metabolic screening present in all states for conditions such as phenylketonuria, galactosemia and many others.

Next came hearing screening and screening for infants less than 37 weeks gestational age in car seats.  The most recent screening is pulse oximetry screening for critical congenital heart defects (CCHD) in newborns.  The American Academy of Pediatrics has recently published this recommendation available at http://pediatrics.aappublications.org/content/128/5/e1259.full.pdf+html.¹  This has already been incorporated into state regulations in Maryland and New Jersey.  Other states are likely to follow.  In many cases, this screening is already in place or is being put into place without state recommendations.

For consideration, the requirements for a screening program and measures of effectiveness are prevalence of the disorder, simple and reliable methods for screening, available treatment and favorable cost/benefit ratio.²  The pulse oximeter screening meets these criteria.  The specific recommendations are that the pulse oximeter be placed on a pre and post ductal location long enough to get a pulse oximeter reading.   The screen should be completed once the infant is at least 24 hours old.  The pre and post-ductal probes do not necessarily need to be placed simultaneously so a single probe can be used per patient.  This cost will vary, of course, based on specific pulse oximeter probes purchased and buying agreements for a specific hospital.  However, either a disposable or non-disposable probe may be utilized, thus possibly decreasing costs further.  Some hospitals may see nursing time as an issue in completing the screening.  However, this may be coupled with other screens or procedures that need to be done, for instance during the car seat monitoring period or with the hearing screen.  The infant should be in a quiet sleep state for both of these tests and both are usually done beyond 24 hours of age.

The latest recommendations include that any value less than 90% be considered a positive screen and lead immediately to further evaluation.  Any value greater than or equal to 95% is considered a negative screen, unless the pre and post ductal difference is greater than 3%.  In the area between 90 and 95% or with a difference greater than 3% between pre and post ductal readings, a repeat measure is performed twice at 1 hour intervals until and unless a reading greater than or equal to 95% or less than 90% is reached.  The recommendations from AAP include a nice flowchart to simplify these values and next actions recommended.

Much discussion is ongoing about how and why to implement these guidelines.  There are older studies that show that many congenital heart defects are not caught until late enough that infants are in extreme distress and, in fact, may not survive.³  Through various studies, the screening has demonstrated effectiveness at screening for hypoplastic left heart, pulmonary atresia with intact ventricular septum, simple transposition of the great arteries or interruption of the aortic arch.  Various other defects were also detected in their most critical form.  These included coarctation of the aorta, aortic valve stenosis, pulmonary valve stenosis, tetrology of Fallot, pulmonary atresia with a ventricular septal defect and total anomalous pulmonary venous connection.⁴  In my own experience, we began screening at least 5 years ago at the recommendation of our pediatric cardiologist.  It was initially considered “one more thing” that must be done prior to discharge for seemingly healthy infants.  However, soon after the program was launched, an infant was identified as having a low saturation (about 92%).  The nurse notified the physician, per the protocol who examined the infant and felt upon initial exam that the infant was not in distress and a cardiac echocardiogram may be excessive.  However, since this was the protocol, it was completed.  The infant was found to have a complex cardiac anomaly and likely would not have survived had the infant been discharged home.  This case early in our experience convinced everyone that the extra time and expense was worth it.  The infant was transferred to a facility where cardiac surgery was performed and ended up doing quite well.

This most recent recommendation from the American Academy of Pediatrics also recommends screening infants in the NICU with a stay of seven (7) days or less.  In most cases, these infants are being monitored with pulse oximetry as a part of their NICU course.  However, the evaluation of pre and post ductal saturation may not have been or be a normal course of care in the NICU.  These infants, discharged before the ductus arteriosus is closed may then be missed by not having this simple screen completed.

References:

1. Kemper AR, Mahle WT, Martin GR, Cooley C, Kumar P, Morrow WR, et al.  Strategies for implementing screening for critical congenital heart disease.  Pediatrics.  2011; 128(5):e1-e9.

2. American Academy of Pediatrics, Newborn Screening Task Force.  Newborn screening: A blueprint for the future.  Pediatrics.  2000;106:389-397.

3. Koppel RI, Druschel CM, Carter T, Goldberg BE, Mehta PN, Talwar R, Bierman FZ.  Effectiveness of pulse oximetry screening for congenital heart disease in asymptomatic newborns.  Pediatrics.  2003; 111(3):451-455.

4. Ewer AK, Middleton LJ, Furmston AT, Bhoyar A, Daniels JP, Thangaratinam S, et al.  Pulse oximetry screening for congenital heart defects in newborn infants (PulseOx): A test accuracy study.  Lancet.  2011; 378:785-794.