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Pulse Ox Frequently Asked Questions

Learn more about pulse oximetry, a simple, non-invasive and painless test.

Critical Congenital Heart Defects: Updated Newborn Screening Guidelines for Parents to Know

Clinicians and medical staff can review proper screening for CHD in this video using pulse oximetry (pulse ox). It's a simple, non-invasive, painless procedure that helps save hundreds of infant lives a year in the U.S.

Explore Frequently Asked Questions

What is pulse oximetry?

Pulse oximetry (ox-eh-mah-tree), or “pulse ox,” is a simple, non-invasive and painless test that is used to measure the percent oxygen saturation of hemoglobin in the arterial blood and the pulse rate. Pulse ox was invented in the 1970s and is now widely used and accepted in clinical care; it is often thought to be a basic vital sign.

How is pulse ox performed?

A pulse oximeter uses a light sensor that a healthcare team member will attach to your baby’s right hand and either foot to measure how much oxygen is in the blood. It does not hurt and takes a few minutes.

What is congenital heart disease (CHD)?

Congenital Heart Disease (CHD) affects the heart’s structure or blood flow and impacts nearly 1 out of every 100 babies born each year. It is the most common birth defect. Some severe cases, called "critical" CHDs, require early detection and intervention, occurring in 1 out of every 4 babies born with CHD (roughly 25% of CHD cases).

What if my baby passes the test?

If your baby passes the test, they can be safely sent home, indicating a low risk for critical congenital heart defects. Regular check-ups with the baby’s doctor are still necessary.

What if my baby does not pass the test?

If your baby does not pass, doctors may conduct further tests, like an echocardiogram (ultrasound of the heart), to take a closer look at the baby’s heart and blood flow. Other tests may be done to understand lower oxygen levels. Your doctor will guide you based on your baby's test results if the reading is low.

When will your baby be screened?

It is recommended for all babies to be screened before they go home. If you are unsure when your baby was screened, ask the nurse or doctor for the results.The test requires the baby to be at least 24 hours old or can take place just before they leave the hospital if going home earlier.

Who should be screened?

All babies in the newborn nursery should be screened. The test will be done after the baby is born when he or she is older than 24 hours. The pulse ox test will be done if the baby isn’t already thought to have a problem with the heart or lungs. The test is non-invasive and painless. Pulse ox screening should be performed while the infant is in the newborn nursery, before they go home.

What is a normal reading?

For healthy babies, readings between 95% to 100% on both hand and foot, with less than 3% difference between the two, are normal. Babies with heart or lung problems may have lower readings or a significant difference between their right hand and either foot.

Can a baby with critical CHD have a normal pulse ox reading?

It is possible that the pulse ox test will not detect all forms of problems in the baby's heart. Your baby should continue to have normal visits with his or her primary care doctor. If a problem with the heart is suspected, your primary care doctor will advise you.

Why is pulse oximetry used to screen for CHD?

Pulse ox is used to measure how much oxygen is in the blood. Pulse ox is a routinely used test that can be used to monitor an baby's oxygen level during a procedure or treatment. It can also be helpful in determining if a baby’s heart and lungs are healthy. Pulse ox can also help to identify babies with low levels of oxygen in their blood that may have serious heart problems. A doctor or nurse practitioner may ask for more testing such as an ultrasound of the heart, or echocardiogram (or “echo”) when a low pulse ox reading is identified. The echo will screen for a serious problem in the structure of the heart or the blood flow through the heart. Pulse ox can help identify a baby with critical CHD before he or she leaves the newborn nursery.

What if I have questions or do not want to have my baby screened for serious heart problems?

If you have questions about pulse ox or CCHD, you should ask the doctor or nurse practitioner who is providing your prenatal care or the doctor or nurse caring for your baby after he or she is born. If you do not want your baby screened for serious heart problems you should tell your doctor or nurse when you are in the hospital to deliver your baby.

What to watch for after screening?

Pulse ox identifies most, but not all babies with CCHD. If your baby passes, but shows signs such as tiredness during feedings, sweating, fast breathing, blueness around the lips and mouth, excessive sleepiness, puffiness, irritability, or difficulty soothing, contact your baby’s doctor promptly.