CCHD screening is a standard part of universal newborn screening, designed to identify serious health conditions shortly after birth. This non-invasive procedure detects specific, life-threatening heart defects before a newborn develops obvious symptoms. The goal is to facilitate early intervention, which can significantly improve health outcomes and reduce the risk of disability or death.
Understanding Critical Congenital Heart Disease
Critical congenital heart disease refers to severe structural heart defects present at birth that interfere with the effective circulation of oxygenated blood. These conditions are critical because they typically require medical or surgical intervention within the first year of life. Without timely diagnosis and treatment, CCHD can lead to shock, organ damage, and life-threatening complications.
The defects often involve complex abnormalities in the chambers, valves, or major blood vessels of the heart. Examples include hypoplastic left heart syndrome (underdeveloped left side of the heart) and transposition of the great arteries (switched main arteries). Other defects, such as Tetralogy of Fallot and total anomalous pulmonary venous return, also fall under this classification.
A major challenge is that many affected newborns appear healthy during their initial hours of life, masking the severity of their condition. This is due to fetal circulation patterns, which temporarily compensate for the heart defect. Once these transitional pathways close, the baby’s condition can rapidly deteriorate, necessitating universal screening for early detection.
How the Pulse Oximetry Screening Works
CCHD screening uses pulse oximetry, a simple, non-invasive technology that measures the percentage of hemoglobin saturated with oxygen. A sensor probe, which emits red and infrared light, is placed on the baby’s skin, typically on the hand and foot. The device calculates the oxygen saturation level by analyzing the light absorbed by the blood’s hemoglobin.
The test is usually performed when the newborn is between 24 and 48 hours old, or just before an early discharge. This timing allows the circulatory system to complete the transition from fetal to newborn circulation, reducing false-positive results. The baby must be calm and settled during the screening to ensure an accurate reading.
A sensor is placed on the right hand to measure pre-ductal oxygen saturation, representing blood flow before it mixes with less oxygenated blood. A second sensor is placed on either foot to measure post-ductal oxygen saturation. Comparing these two measurements is essential, as a significant difference between the pre- and post-ductal saturation can indicate structural heart issues affecting blood flow.
Interpreting Screening Results and Next Steps
The pulse oximetry screening yields one of three possible results: a pass (negative screen), an inconclusive result requiring a repeat test, or a fail (positive screen).
A newborn passes the screen 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. While reassuring, a pass result does not rule out all heart defects, so parents must remain vigilant for symptoms after discharge.
A result is a clear failure, requiring immediate referral, if the oxygen saturation measurement is less than 90% in either the hand or the foot. This low saturation level suggests severe hypoxemia (low blood oxygen), mandating urgent medical evaluation.
An inconclusive result occurs if the saturation is between 90% and 94% in both extremities, or if the difference between the hand and foot saturation is greater than 3%. The test must be repeated after one hour to allow oxygen levels to stabilize. If the repeat screen remains inconclusive or fails, the newborn receives a positive screen result.
A positive screen, whether an immediate fail or a confirmed repeat, is a referral for further evaluation, not a definitive diagnosis. The immediate next step is an urgent referral for a diagnostic echocardiogram and consultation with a pediatric cardiologist. The echocardiogram, an ultrasound of the heart, provides the detailed imaging necessary to confirm or rule out a specific critical heart defect.