How is CHD diagnosed in newborns? 

Congenital Heart Disease (CHD) in newborns is primarily diagnosed through a combination of physical examinations, pulse oximetry screening, and specialized imaging like echocardiograms. While many defects are identified during the routine 20-week prenatal scan, postnatal screening is essential for detecting ‘critical’ CHD that may only become apparent once the baby begins breathing independently. Early diagnosis is vital to ensure timely intervention and improve long-term survival rates. 

Congenital heart disease diagnosis in the neonatal period focuses on identifying structural abnormalities as the infant transitions from fetal to newborn circulation. In the UK, the NHS implements a systematic approach to screening, ensuring that every newborn undergoes a physical check within 72 hours of birth. This process is designed to catch defects that might not have been visible on prenatal ultrasounds, such as small septal holes or narrowing of the heart valves. Early detection is particularly important for critical CHD (cCHD), which requires surgery or intervention within the first year of life. 

What We’ll Discuss in This Article 

• The role of the Newborn Physical Examination (NIPE). 

• How pulse oximetry screening detects low oxygen levels. 

• The use of echocardiograms as the ‘gold standard’ for diagnosis. 

• Recognising clinical signs like heart murmurs and cyanosis. 

• The difference between prenatal and postnatal heart screening. 

• NHS protocols for specialist referral and cardiac monitoring. 

The Newborn Physical Examination (NIPE) 

The first line of defense in diagnosing CHD is the Newborn Physical Examination (NIPE), which is typically carried out within 72 hours of birth. During this check, a trained healthcare professional listens to the baby’s heart with a stethoscope to detect ‘heart murmurs’ unusual sounds caused by turbulent blood flow. While many murmurs in newborns are innocent, they can also be the first clinical sign of an underlying structural defect. 

In addition to listening to the heart, the clinician checks the ‘femoral pulses’ in the baby’s groin. Weak or absent pulses can indicate a condition called coarctation of the aorta, where the main artery is too narrow. The examination also looks for signs of ‘cyanosis’ (a blue tinge to the skin) and assesses the baby’s breathing rate. According to the NHS NIPE standards (2024), this physical check is a critical safety net for identifying symptomatic heart defects early. 

Pulse Oximetry: Screening for Critical CHD 

Pulse oximetry is a non-invasive test that measures the amount of oxygen in a baby’s blood. It is a highly effective tool for detecting critical congenital heart disease (cCHD) that may not be accompanied by a heart murmur or visible cyanosis. The test involves placing a small sensor on the baby’s hand and foot to compare oxygen saturation levels. 

The table below outlines how pulse oximetry results are typically interpreted in a clinical setting: 

Oxygen Saturation (%)	Clinical Interpretation	Action Required
95% or Higher	Normal	No further cardiac action (if NIPE is normal)
90% to 94%	Borderline	Repeat test in 1–2 hours
Less than 90%	Abnormal	Immediate specialist review and echocardiogram
>3% difference (hand vs foot)	Potential defect	Referral for further cardiac investigation

Pulse oximetry is particularly useful for detecting ‘duct-dependent’ lesions. These are defects where the baby remains stable while the ductus arteriosus (a fetal blood vessel) is open, but becomes rapidly unwell once it closes shortly after birth. 

Echocardiogram: The Gold Standard for Diagnosis 

If a physical exam or pulse oximetry screening suggests a problem, the definitive diagnosis is made using an echocardiogram. This is an ultrasound of the heart that allows cardiologists to see the heart’s structure, chambers, and valves in real-time. It is the most accurate way to confirm the presence and severity of CHD. 

• Non-invasive: The test uses sound waves and is completely painless for the baby. 

• Detailed Mapping: It shows how blood flows through the heart (Doppler) and identifies holes in the walls or narrow valves. 

• Speed: In emergency situations, a ‘bedside’ echo can be performed in the Neonatal Intensive Care Unit (NICU) to provide an immediate diagnosis. 

Differentiating Between Innocent and Pathological Murmurs 

It is common for newborns to have heart murmurs, and it is important to differentiate between those that are ‘innocent’ and those that indicate a ‘pathological’ defect. An innocent murmur is simply the sound of blood moving through a healthy heart, often appearing because the baby’s heart is close to the chest wall. 

• Innocent Murmurs: Usually quiet, occur during a specific part of the heart cycle, and the baby remains otherwise healthy and pink. 

• Pathological Murmurs: Often louder, may be associated with a ‘thrill’ (a vibration felt on the chest), and are frequently accompanied by symptoms like fast breathing or poor feeding. 

• Clinical Statistics: Roughly 50% of newborns may have a murmur at some point, but only a small fraction of these represent a structural heart defect. 

Conclusion 

Diagnosing CHD in newborns relies on a multi-layered approach involving the physical examination, pulse oximetry, and echocardiography. While most babies are born with healthy hearts, these screening tools are essential for catching the 1 in 100 infants who have a structural defect. Early identification allows for specialized care pathways, ensuring that even the most complex heart conditions can be managed effectively from day one. 

If your baby has difficulty breathing, a blue tinge to their lips, or is too tired to feed, call 999 immediately. 

If you notice your baby is unusually pale, cold to the touch, or extremely lethargic, call 999 immediately. 

You may find our free Pregnancy Due Date Calculator helpful for understanding the timeline of fetal heart development leading up to birth. 

Authority Snapshot (E-E-A-T Block) 

This article was reviewed by Dr. Stefan Petrov, a UK-trained physician (MBBS) with postgraduate certifications in ACLS and BLS. Dr. Petrov has extensive experience in hospital wards and intensive care units, where he has performed and assisted in neonatal assessments. His background in medical education ensures that this information on newborn CHD diagnosis is accurate, safe, and aligned with current NHS and NIPE clinical standards.