Newborn Pulse Oximetry for Detection of Congenital Heart Disease at Tertiary health care Centre

Technical Summary: Newborn Pulse Oximetry for Detection of Congenital Heart Disease at a Tertiary Health Care Centre

Problem Statement
Congenital heart disease (CHD) is the most common congenital anomaly and a leading cause of neonatal morbidity and mortality. A significant proportion of critical congenital heart disease (CCHD) remains undetected at birth when relying solely on antenatal screening and clinical examination. Many infants with CCHD appear clinically well during the immediate postnatal period ("silent period") and may only present with life-threatening complications after the ductus arteriosus closes. In resource-limited settings like India, access to high-quality antenatal cardiac screening is limited, and postnatal clinical examination has shown limited sensitivity, with studies suggesting up to 30–50% of CCHD cases may be discharged without diagnosis. There is a need for a simple, non-invasive, and effective screening tool to bridge this diagnostic gap.

Methodology
This prospective observational cohort study was conducted at a tertiary care teaching hospital in Maharashtra, India, over a two-year period (May 1, 2024, to April 30, 2026).

• Population: The study included 13,120 term newborns (gestational age 37–42 weeks) with normal birth weights (2.5–4.0 kg). Preterm infants, those with known chromosomal abnormalities, critical respiratory illnesses, or prenatally diagnosed CHD were excluded.
• Screening Protocol: Pulse oximetry screening was performed between 24 and 48 hours of life. Oxygen saturation (SpO₂) was measured at two sites: the right hand (pre-ductal) and a foot (post-ductal).
• Screening Criteria: A screen was considered positive if:
  1. SpO₂ was <95% in either extremity, OR
  2. The difference between pre-ductal and post-ductal saturation was ≥3%.
• Diagnostic Confirmation: Screen-positive newborns underwent detailed diagnostic evaluation, including echocardiography (the gold standard), ECG, and chest X-ray. Small septal defects (<5 mm) and small patent foramen ovale were considered physiologically insignificant and classified as false positives.
• Data Analysis: Demographic, clinical, and antenatal characteristics of screen-positive neonates were analyzed. The spectrum of cardiac lesions and the association between clinical presentation, delivery mode, and risk factors were evaluated using Chi-square tests.

Key Results

• Screening Yield: Out of 13,120 newborns screened, 45 (0.34%) were identified as screen-positive.
• Diagnostic Outcomes: Among the 45 screen-positive infants:
  • True Positives: 40 infants (88.9%) had clinically significant CHD.
  • False Positives: 5 infants (11.1%) had physiologically insignificant lesions (small ASD, VSD, or PFO).
  • Critical vs. Non-Critical: 31 infants (68.9%) had Critical CHD (CCHD), and 14 (31.1%) had Non-Critical CHD.
• Spectrum of Disease: The most common lesions were Tetralogy of Fallot (26.7%), Double Outlet Right Ventricle (15.6%), and Dextro-Transposition of the Great Arteries (13.3%). Duct-dependent lesions such as Hypoplastic Left Heart Syndrome were also detected.
• Clinical Presentation: 73.3% of affected infants were symptomatic (primarily cyanosis), while 26.7% were asymptomatic at the time of detection. Notably, 2 infants with Critical CHD were asymptomatic.
• Demographics: The majority of affected infants were term (mean gestational age 38.1 weeks) and had normal birth weights (mean 2.86 kg). There was no statistically significant association between the mode of delivery and the type of CHD.
• Risk Factors: While 41/45 cases (91.1%) lacked a family history of CHD, identifiable maternal antenatal risk factors were present in 13 cases (28.9%). These included oligohydramnios (4 cases), pregnancy-induced hypertension (3 cases), gestational diabetes mellitus (3 cases), rubella/CMV (1 case), and polyhydramnios (1 case). Oligohydramnios was the most frequent risk factor observed in the critical CHD group, while Pregnancy-Induced Hypertension was associated with non-critical CHD.
• Complexity: 91.1% of the diagnosed cases involved multiple congenital heart defects, while only 8.9% had isolated single defects.

Significance and Claims
The study concludes that newborn pulse oximetry screening is an effective, feasible, and highly specific method for the early detection of CHD, particularly critical lesions, in term neonates.

• Detection of Silent Cases: The identification of asymptomatic infants, including those with critical lesions, underscores the limitation of relying solely on clinical examination and supports the necessity of objective physiological screening before discharge.
• Targeting Critical Lesions: The high proportion of Critical CHD (68.9%) among screen-positive cases demonstrates that pulse oximetry preferentially detects the most life-threatening conditions that require urgent intervention.
• Universal Applicability: Since the majority of affected infants were term, normal-weight, and lacked family history or antenatal risk factors, the study argues against selective screening based on risk stratification. Instead, it advocates for universal implementation to prevent missed diagnoses.
• Resource-Limited Context: The study highlights that in settings with limited antenatal diagnostic capabilities, universal pulse oximetry screening can significantly reduce missed diagnoses, facilitate timely referral, and improve neonatal outcomes.

Limitations
The authors acknowledge that the study's sensitivity and specificity could not be fully calculated because echocardiography was not performed on screen-negative newborns. Additionally, the exclusion of preterm and low-birth-weight infants limits the generalizability of the findings to the entire newborn population. The study was conducted at a single tertiary center, which may introduce referral bias. Finally, the method primarily detects hypoxemia-associated defects and may miss acyanotic CHD.