The Critical Congenital Heart Disease (CCHD) screening is a standard, non-invasive procedure performed on newborns before they leave the hospital. This test is designed to identify serious heart defects that often do not show visible symptoms at birth. By measuring blood oxygen levels, the screening acts as an early warning system for conditions that could become life-threatening shortly after a baby goes home.
Understanding Critical Congenital Heart Disease
Critical Congenital Heart Disease refers to structural heart defects that form during fetal development, affecting approximately 18 out of every 10,000 births annually. These malformations impede the heart’s ability to pump blood or deliver sufficient oxygen to the body’s tissues. Conditions like Hypoplastic Left Heart Syndrome or Transposition of the Great Arteries require intervention within the first few weeks or months of life.
Many babies with CCHD appear healthy because the ductus arteriosus, a temporary blood vessel, remains open, allowing blood to bypass the defect. Once this vessel naturally begins to close, typically a few days after birth, the baby’s condition can rapidly and unexpectedly deteriorate. Early detection is necessary, as a delayed diagnosis can lead to shock, organ damage, or death. The screening aims to identify these asymptomatic infants so they can receive treatment before the ductus arteriosus closes.
How the Pulse Oximetry Screening is Performed
The CCHD screening is performed using pulse oximetry, a painless method for measuring the percentage of oxygen saturation in the blood. This screening is ideally conducted when the infant is between 24 and 48 hours old. Performing the test after the first 24 hours allows the baby’s circulatory system to stabilize following the transition from fetal to newborn circulation, reducing the chance of a false-positive result.
The procedure involves placing sensors on two locations: the right hand and one of the feet. Readings taken from the right hand are considered “pre-ductal,” as the blood measured there has not yet passed through the ductus arteriosus. The sensor placed on the foot provides a “post-ductal” reading, representing blood that has circulated past the ductus arteriosus. The difference between these two readings indicates potential heart defects that cause a lower oxygen saturation in the body’s lower half. The process typically takes only a few minutes to get a stable reading from both sites.
Interpreting Results and Necessary Follow-Up Care
The pulse oximetry screening results are classified into a “Pass,” a “Fail,” or a “Repeat” result, based on specific oxygen saturation percentages and the difference between the two limb readings. An infant passes the screening if the oxygen saturation is 95% or greater in both the right hand and the foot, and the absolute difference between the two readings is 3% or less. A passing result does not eliminate the possibility of a non-critical heart defect that may not cause low oxygen levels.
A failed result occurs if the oxygen saturation is less than 90% in either limb, or if the difference between the hand and foot reading is greater than 3%. If the reading is between 90% and 94% in both limbs, or if the difference is between 4% and 10%, a repeat screen is performed within one hour to confirm the initial finding. A definitive “Fail” result indicates the baby requires immediate, further evaluation because of hypoxemia, or low blood oxygen.
This follow-up typically includes a thorough physical examination and diagnostic tests, most often an echocardiogram, which is an ultrasound that provides detailed images of the heart’s structure and function. Other tests, like a chest X-ray or blood work, may also be ordered to rule out non-cardiac causes of low oxygen, such as respiratory issues or infection. The goal is to identify the precise cause of the failed screening, ensuring that any infant with CCHD receives consultation with a pediatric cardiologist and life-saving management before hospital discharge.