Common Questions

When a baby is born, doctors do a special test called pulse oximetry to check how much oxygen is in their blood. This helps find serious heart problems early. Here are some common questions new parents ask:

Answers to Common Questions from Families

Question:Will this test find all serious heart problems?

No. This test finds many heart problems that cause low oxygen in the baby’s blood, but not all of them. Some babies look healthy at birth but can get very sick a few days later. The test works best for these heart problems:

Hypoplastic Left Heart
Pulmonary Atresia
Tetralogy of Fallot
TAPVR (Total Anomalous Pulmonary Venous Return)
Transposition of the Great Arteries
Tricuspid Atresia
Truncus Arteriosus

It may also find:

Coarctation of the Aorta
Double Outlet Right Ventricle
Ebstein’s Anomaly
Interrupted Aortic Arch
Single Ventricle

Some heart problems don’t lower oxygen levels, so this test won’t find them.

Question:Can this test find other problems?

Yes.This test can find other problems that cause low oxygen in the baby’s blood. These problems are also important to know about so the baby can be treated. These problems can include:

Issues with their lungs
Problems with their red blood cells
Infections
Other causes that lead to low blood oxygen levels

Question:Does this test replace other ways to find heart problems?

No. Most serious heart problems are found before birth with an ultrasound or after birth during a doctor’s exam. Pulse oximetry is just one more way to catch problems that might be missed.

Question:Can a baby with a healthy heart fail the test?

Yes, but it’s rare. If the test is done after the baby is 24 hours old, and if the baby gets two chances to pass, very few healthy babies will fail. Sometimes babies fail the test because of other issues like breathing problems or infections. If a baby fails, a doctor will check to find out why.

Question:Why does the timing of the test matter?

A baby’s oxygen levels slowly rise in the first day after birth. If the test is done too early, a healthy baby might fail. By 24 hours, most babies have oxygen levels above 95%, which is normal.

Question:What happens if a baby fails the test?

Doctors will check the baby for other health problems first. If they don’t find another reason for low oxygen, they will check the baby’s heart using a test called an echocardiogram (a special ultrasound of the heart).

Question:Are other tests helpful if a heart scan can’t be done?

Sometimes doctors use chest X-rays, heart rhythm tests, or lab tests to look for infections or other problems. These can help, but they don’t rule out a serious heart problem.

Question:What if the hospital can’t do a heart scan?

In some small hospitals, the echocardiogram may not be available. In that case, the doctor may talk to a heart specialist and may send your baby to another hospital for testing. Sometimes the baby can stay a little longer for more checks.

Question:What if my baby is in the NICU?

Babies in the NICU (Neonatal Intensive Care Unit) also get tested. If your baby is getting extra oxygen, they’ll do the pulse oximetry test once your baby doesn’t need that oxygen anymore. If your baby needs to go home with extra oxygen, an echocardiogram may be done before you go home.

Question:Is this test required by law?

Yes, in Wisconsin this test has been required since 2014. All babies must be tested unless the parents refuse for religious or personal reasons. This test helps keep babies healthy by finding serious heart problems early.

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