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POX Screening Decision Tool

Pulse Oximetry FAQ

“I understand why it is a good idea to screen for Critical Congenital Heart Disease, but what is pulse oximetry screening, and how, when and where will this screening test be done?“

Pulse Oximetry Screening: Basic Facts

If you have questions that are not answered here, or if you would like more information about this screen, please ask your medical care provider or contact the Wisconsin SHINE Project.

Question:Who should be screened?

All babies born in Wisconsin should be screened for Critical Congenital Heart Disease, including babies admitted to the NICU and babies born outside the hospital.

Question:What is Pulse Oximetry Screening?

Pulse oximetry is a painless and non-invasive way to measure the amount of oxygen in blood. Light is passed through the skin and measured by a sensor to determine the percent oxygen saturation. Babies with an abnormally low oxygen saturation in their blood will need further testing for critical congenital heart disease or other problems which can cause low oxygen saturations.

Question:When should babies be screened?

Many normal newborns have oxygen saturations lower than 95-100% in the first hours of life as their bodies adjust to life outside the womb. By 24 hours of life this transition period should be done and oxygen saturations should be 95% or greater. Pulse oximetry screening should always be done after 24 hours to avoid falsely labeling a baby as failing the screening test.

Some babies require supplemental oxygen after they are born. In this case, screening should be delayed until the baby no longer needs extra oxygen. If a baby is going home on supplemental oxygen, pulse oximetry screening for CCHD should be done prior to discharge.

Question:Where should babies be screened?

A pulse oximetry probe will measure the oxygen saturation in the right hand and in either of the feet. Measuring in these two places gives a more accurate picture of the function of the heart.

Question:How are babies screened?

 “Two Sites, Three Strikes” is the easiest way to understand CCHD screening:

Two Sites A pulse oximetry probe will measure the oxygen saturation in the right hand and the right or left foot. Measuring in these two places gives a more accurate picture of the function of the heart.
Three Strikes A baby has three chances to pass pulse oximetry screening unless they are found to have very low oxygen saturation (<90%) in the hand or the foot at any point in the screening process.
Question:How does a baby pass or fail the screen?
Pass Pulse oximetry reading greater than 95% in either hand or foot and difference between hand and foot <= 3% is an immediate pass and no further testing is needed.
Fail Pulse oximetry reading less than 90% anywhere anytime is an immediate fail and baby requires further evaluation.
Repeat If the pulse oximetry reading is between 90-94% in right hand AND foot or if there is >3% difference between two sites the screen will be repeated one hour later. At the repeat screen the baby can pass, fail, or require one more repeat screen an hour later. After the third screen the baby must either pass or fail. Pulse oximetry between 90-94% in right hand AND foot or  >3% difference between two sites on the third screen is considered a fail.