CCHD screening is a simple pulse oximetry test performed on newborns to detect critical congenital heart defects before a baby leaves the hospital. The test measures oxygen levels at two sites on the baby’s body, takes only a few minutes, and is now required in all 50 U.S. states. Here’s how the screening works from start to finish.
When to Screen
The screen should be performed when the baby is at least 24 hours old. Screening earlier than this increases the chance of a false positive because many healthy newborns have slightly lower oxygen levels during the first day as their circulatory system transitions to life outside the womb. If the baby will be discharged before 24 hours, the screen should be done as late as possible before discharge.
Equipment You Need
You need a pulse oximeter that meets several specific requirements. The device must be FDA-cleared for use on newborns, motion-tolerant (since babies move unpredictably), and validated to work in low-perfusion conditions, meaning it can still get an accurate reading when blood flow to the extremities is weak. It should report functional oxygen saturation and have a root-mean-square accuracy of 2% or better. Standard adult pulse oximeters do not meet these criteria. Neonatal-specific sensors, which are smaller wraps designed for tiny hands and feet, are also essential for getting a reliable reading.
Where to Place the Sensors
The screen requires two separate oxygen saturation readings: one pre-ductal and one post-ductal. In practical terms, this means placing one sensor on the right hand and the other on either foot. The right hand reflects oxygen levels in blood that has not yet passed through the ductus arteriosus (a small vessel that connects two major arteries in newborns), while the foot reflects blood that has passed through it. A significant difference between these two readings can signal that oxygen-poor blood is being sent to the body, which is a hallmark of several critical heart defects.
The baby should be calm and warm, with good circulation to the extremities. Cold hands or feet can produce unreliable readings. Wait for the oximeter to display a stable waveform and a consistent number before recording the result.
How to Interpret the Results
The updated American Academy of Pediatrics algorithm, published in late 2024, sets clearer thresholds than the original 2011 version. A baby passes the screen when oxygen saturation is 95% or higher in both the right hand and the foot, and the difference between the two readings is 3 percentage points or less.
A result is considered a screen failure if oxygen saturation is below 90% in either location. This is an immediate fail with no retest needed.
Results that fall between these values are indeterminate. This includes readings of 90% to 94% in either site, or a difference greater than 3 percentage points between the right hand and the foot, even if both individual numbers are above 95%. Under the updated algorithm, you perform one retest. The previous protocol allowed two retests, but the AAP reduced this to one to speed up the path to diagnosis when something is wrong.
What Happens After a Failed Screen
A failed screen does not automatically mean the baby has a heart defect. It means the baby needs prompt, careful evaluation by experienced pediatric staff. The most common next step is an echocardiogram, which is an ultrasound of the heart, and referral to a pediatric cardiologist. However, a positive result is not an automatic trigger for echocardiography in every case. Some experts recommend that the first response be a thorough clinical assessment, because low oxygen levels in a newborn can also be caused by non-cardiac conditions like respiratory problems, infection, or simply incomplete transition from fetal circulation.
The screening has, in fact, proven valuable for catching these non-cardiac conditions early as well. A baby who fails the CCHD screen but turns out to have a lung issue or sepsis still benefits from faster detection and treatment.
Conditions the Screen Detects
The pulse oximetry screen is designed to catch heart defects severe enough to require surgery or catheter-based intervention within the first year of life. These include conditions where oxygen-rich and oxygen-poor blood mix abnormally, where major vessels are switched or narrowed, or where one side of the heart is severely underdeveloped. The screen is not designed to detect every type of congenital heart defect. Defects that do not significantly lower oxygen saturation, such as a small hole between the heart’s chambers, will typically not be caught by pulse oximetry alone.
Reducing False Positives
The single most effective way to reduce false positive results is to wait until the baby is at least 24 hours old. Beyond timing, ensuring the baby is warm and settled before testing helps produce reliable readings. Using the correct neonatal sensors on a properly calibrated, motion-tolerant oximeter also matters. Screening during active crying or movement can produce artificially low readings. If the first reading is borderline, the built-in retest provides a second chance to distinguish a true problem from a temporary fluctuation.
Why Protocol Adherence Matters
The AAP’s 2024 clinical report emphasized that the accuracy of CCHD screening depends heavily on following the protocol precisely. Sensor placement on the wrong hand (left instead of right), testing too early, or skipping the retest interval all undermine the screen’s reliability. State newborn screening programs are now encouraged to collect a standardized minimum dataset from each screen, including the exact oxygen levels, timing, and follow-up actions, to monitor how well the protocol is being followed across hospitals and birthing centers. Staff education on both the steps and the limitations of screening remains one of the AAP’s core recommendations.