Biliary Atresia
The most likely diagnosis is biliary atresia (B), given the classic triad of deep jaundice, pale (acholic) stools, and an otherwise healthy-appearing infant at 2 months of age. 1
Clinical Reasoning
The presentation of persistent jaundice with pale stools at 2 months of age is pathognomonic for biliary obstruction, specifically biliary atresia. Here's why this diagnosis takes priority:
Key Diagnostic Features Supporting Biliary Atresia
Acholic (pale) stools are the hallmark clinical finding that distinguishes biliary atresia from other causes of neonatal cholestasis, including neonatal hepatitis and metabolic disorders 1
Jaundice persisting beyond 2-3 weeks with conjugated hyperbilirubinemia defines pathologic neonatal cholestasis requiring immediate intervention 1, 2
The infant appears healthy and is growing well, which is typical in early biliary atresia before progressive liver dysfunction develops 1, 3
Dark urine would be expected (though not mentioned in the question) due to renal excretion of water-soluble conjugated bilirubin 1, 3
Why Other Options Are Less Likely
Neonatal hepatitis (A):
- Typically presents with variable stool color rather than consistently pale stools 1
- Would show hepatocellular injury pattern rather than pure cholestatic obstruction
- Less common than biliary atresia as a cause of neonatal cholestasis 4
TORCH infection (C):
- Usually presents with additional systemic findings (microcephaly, hepatosplenomegaly, thrombocytopenia, growth restriction) 3
- The infant appears healthy and growing well, making this unlikely
- Would not typically cause acholic stools
Galactosemia (D):
- Presents acutely in the first weeks of life with poor feeding, vomiting, hepatomegaly, and failure to thrive 5
- The infant is described as healthy and growing well, which excludes this diagnosis
- Would show reducing substances in urine and hypoglycemia
Critical Management Implications
This is a surgical emergency. 1, 4
The Kasai portoenterostomy must be performed ideally before 60 days of age to maximize success and prevent the need for liver transplantation 1
Any conjugated bilirubin >25 μmol/L (>1.0 mg/dL) requires urgent evaluation for biliary atresia or other cholestatic disease 1
Urgent hepatobiliary ultrasound, hepatobiliary scintigraphy (HIDA scan), and liver biopsy are necessary for diagnosis 1, 2
Failure to treat results in hepatic fibrosis and death within the first year 2, 4
Common Pitfall to Avoid
Do not assume normal ultrasound rules out biliary atresia - normal ultrasound scans cannot exclude this diagnosis 4. The diagnosis requires operative findings and intraoperative cholangiogram for confirmation 4, 6.