Conjugated jaundice and neonatal cholestasis: SAQ

This infant presents at six weeks with the pathognomonic triad of biliary atresia: acholic (pale, putty-coloured) stools, dark urine staining the nappy, and progressive jaundice in an infant who initially appeared well. The conjugated bilirubin fraction of 120 micromol per litre (67 per cent of total) confirms cholestasis, which is always pathological. The failure to thrive and firm hepatomegaly further support evolving liver disease. [1]

Question 1 (10 marks)

Outline your diagnostic approach and the specific investigations you would organise for this infant. [1]

The conjugated fraction is above 17 micromol per litre and more than 20 per cent of total, confirming cholestasis and triggering the full diagnostic panel. Alongside the bilirubin, send a full liver panel including alanine and aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transferase, albumin, and coagulation studies. A high gamma-glutamyl transferase favours obstruction or biliary atresia over an intrahepatic cause. Check the coagulation profile urgently and give intravenous vitamin K 1 milligram if the international normalised ratio is prolonged, before any invasive procedure. [1]

Run the metabolic and infective panel in parallel: glucose for hypoglycaemia, ammonia if metabolic disease is plausible, a full septic screen, TORCH and urine cytomegalovirus polymerase chain reaction, alpha-1-antitrypsin phenotype and level, galactosaemia and tyrosinaemia markers, thyroid function, urine reducing substances, and alpha-fetoprotein. Imaging begins with a fasted abdominal ultrasound looking for a small or absent gallbladder and the triangular cord sign, but a normal ultrasound does not exclude biliary atresia. The definitive diagnostic test is an intraoperative cholangiogram, and a percutaneous liver biopsy showing bile-duct proliferation, portal fibrosis, and bile plugs supports the diagnosis of biliary atresia. [2]