Pulse oximetry (also called pulse ox) is a simple and painless test that measures how much oxygen is in the blood. The test can be used to monitor a baby's oxygen level during a procedure or treatment, and it can also be helpful in determining if a baby's heart and lungs are healthy.
In 2011, the Secretary of Health and Human Services (HHS) recommended that critical congenital heart disease (CCHD) be added to the standard-of-care screening tests performed on newborns. In the same year, the American Academy of Pediatrics (AAP) released a statement of endorsement for the HHS recommendations and provided an algorithm to detect infants with CCHD as early as possible.
Why is early screening for CCHD so important?
Most babies are born with healthy hearts, and have enough oxygen in their blood. About 1 baby in 100 is born with heart defect. Approximately ¼ of these children will have CCHD—when a baby's heart or major blood vessels do not form properly. A critical defect is one that needs urgent treatment to have the best outcome.
Some babies with CCHD are diagnosed with their heart defect during the pregnancy by an ultrasound, but many are not diagnosed until after they are born. Ultrasounds during pregnancy do not detect all types of heart defects.
Babies born with CCHD may look and act healthy at first, but within hours or days after birth they can have serious complications if left untreated. Measuring the oxygen level in the baby can help detect the heart defect. Screening a newborn using pulse oximetry makes it possible for the heart defect to be identified early—before the baby gets sick from the defect. Early detection and appropriate management can then be provided and may improve a baby's outcome.
How is newborn screening for CCHD different than other newborn screening tests?
Each newborn screening tests for different problems. The hearing test looks for hearing problems, the phenylketonuria (PKU) test looks for metabolic problems, and so on.
In the US, nearly all states have adopted universal newborn screening for CCHD. Requirements for screening vary from state to state. Some states have taken an active role in ensuring all newborns are screened by requiring screening, determining when screening should occur, what data must be reported, etc. Other states, however, have taken a less active role in implementation.
Check out your state's actions on newborn screening for CCHD here.
How is screening for CCHD done?
A small soft sensor is wrapped around the baby's right hand and one foot to measure the heart rate and oxygen level in the blood. It is fast, easy, and does not hurt.
The pulse oximetry screening occurs after 24 hours after birth to allow the baby's heart and lungs to fully adjust to life outside his or her mother. After the screening is completed, the doctor or nurse will go over the reading with the baby's parents.
What happens a baby fails the pulse oximetry screening?
If the screening test suggests a problem, the doctor will speak directly with the parents and will order follow-up testing before a baby is discharged from the hospital. This may include an echocardiogram ("echo)—an ultrasound of the heart. The heart echo will screen for a serious problem in the structure of the heart or the blood flow through the heart and is read by a pediatric cardiologist. If the heart echo shows any problems, the baby's medical team will discuss next steps with the parents.
Note: As with any screening test, both false positives and false negatives can occur. The screening algorithm developed be the AAP was designed to balance the false positives (e.g., unnecessarily worrying the family) against the harms of false negatives (e.g., delayed detection of CCHD). Just because a baby fails the pulse oximetry screening test does not mean that the baby has a heart defect. There are other reasons that a baby may have lower oxygen levels, such as infection or lung problems. Some healthy babies can have a low pulse oximetry reading while their heart and lungs are adjusting after birth.
If a baby passes the pulse oximetry screening, does it mean he or she has no heart defects?
Unfortunately, no. Pulse oximetry testing picks up only some types of heart defects. Some heart defects do not change blood oxygen levels and are not picked up by the test.
Even if a baby passes the pulse oximetry screening, parents should watch:
How well their baby is feeding
Any difficulty in breathing
Bluish color to the lips or skin
Poor weight gain
Parents are advised to contact their baby's doctor right away if they notice any of these signs.
Additional Information & Resources: