Newborn screening for critical CHDs involves a simple bedside test called pulse oximetry. This test estimates the amount of oxygen in a baby’s blood. Low levels of oxygen in the blood can be a sign of a critical CHD. The test is done using a machine called a pulse oximeter, with sensors placed on the baby’s skin. The test is painless and takes only a few minutes.

CCHD is a group of serious heart conditions present at birth. Children with CCHD have any of a wide range of heart problems that arise when parts of the heart do not form correctly.

In some forms of CCHD, the heart has trouble delivering oxygen from the lungs to the rest of the body. Babies with these forms of CCHD have low levels of oxygen in their blood. Measuring your baby’s blood oxygen level can help see if your baby needs urgent heart treatment.

Some babies born with a critical CHD appear healthy at first, and they may be sent home before their heart defect is detected. These babies are at risk of having serious complications within the first few days or weeks of life, and often require emergency care. Newborn screening is a tool that can identify some of these babies so they can receive prompt care and treatment. Timely care may prevent disability or death early in life.

Following is a step-by-step guide explaining how pulse oximetry screening happens:

• Between 24 and 48 hours after birth, a health care provider will tell you that it is time for your newborn’s pulse oximetry screening.
• The health care provider will place a small wrap on your baby’s skin, usually around the right hand or wrist and on either foot. One side of the wrap has a light, and the other has a sensor.
• The health care provider will connect the wrap to a monitor that uses the sensor’s reading to calculate how much oxygen is in your baby’s blood. Using the numbers on this monitor, the health care provider can tell whether your baby might have CCHD.
• Babies who do not pass pulse oximetry screening the first time may repeat it or may need further testing.

Results from pulse oximetry screening are ready as soon as the screening is done.

No special preparations are necessary. Your baby must be at least 24 hours of age to allow his or her lungs and heart to adapt to life outside the womb.

No risks are associated with this test.

Pulse oximetry screening is most likely to detect seven of the critical CHDs. These seven defects are hypoplastic left heart syndrome, pulmonary atresia, tetralogy of Fallot, total anomalous pulmonary venous return, transposition of the great arteries, tricuspid atresia, and truncus arteriosus. Other heart defects can be just as severe as these seven and also require treatment soon after birth. However, pulse oximetry screening may not detect these heart defects as consistently as the seven listed above.

Pass

If the baby passes the screen (also called “negative” or “in-range” result), it means that the baby’s test results did not show signs of a low level of oxygen in the blood. A baby that passes the screen is unlikely to have a critical CHD. However, not all babies with a critical CHD will have a low level of oxygen in the blood that is detected during newborn screening. Thus, it is possible for a baby who passes the screen to still have a critical CHD or other CHD.

Fail

If the baby fails the screen (also known as “positive” or “out-of-range” result), it means that the baby’s test results showed low levels of oxygen in the blood, which could be a sign of a critical CHD. This does not always mean that the baby has a critical CHD but could mean that more testing is needed. There may be other causes, such as breathing problems, for low levels of oxygen in the blood. The baby’s doctor might recommend that the baby get screened again or have more specific tests, like an echocardiogram (an ultrasound picture of the heart), to diagnose a critical CHD.

Your baby’s health care provider will help decide what test(s) your baby needs.

Pulse oximetry screening does not replace a complete history and physical examination, which sometimes can detect a critical CHD before oxygen levels in the blood become low. Pulse oximetry screening, therefore, should be used along with the physical examination.