A 2 month baby presents with history of jaundice, turmeric colored urine and pale stools since birth. Examination reveals liver span of 10 cms. The most specific investigation for establishing the diagnosis would be –
**Core Concept**
The clinical presentation of a 2-month-old baby with jaundice, turmeric-colored urine, and pale stools, along with an enlarged liver span, is suggestive of biliary atresia. Biliary atresia is a congenital or acquired obstruction of the bile ducts, leading to bile accumulation in the liver, causing jaundice, and liver damage.
**Why the Correct Answer is Right**
The definitive diagnosis of biliary atresia is established by demonstrating the absence of bile ducts or their obstruction. **Hepatobiliary iminodiacetic acid (HIDA) scan**, also known as a cholescintigraphy, is the most specific investigation for establishing the diagnosis. This imaging test involves the intravenous administration of a radioactive tracer that is taken up by the liver and excreted into the bile. In cases of biliary atresia, the tracer does not flow into the intestines, indicating a blockage in the bile ducts.
**Why Each Wrong Option is Incorrect**
**Option A:** Ultrasound of the abdomen may show an enlarged liver and bile duct dilatation, but it cannot definitively diagnose biliary atresia.
**Option B:** Liver function tests (LFTs) may indicate liver damage, but they are non-specific and cannot confirm the diagnosis of biliary atresia.
**Option C:** Abdominal X-ray may show an enlarged liver, but it is not specific for diagnosing biliary atresia.
**Clinical Pearl / High-Yield Fact**
Biliary atresia is a medical emergency that requires prompt diagnosis and treatment to prevent liver cirrhosis and death.
**Correct Answer:** C. HIDA scan