<prompt> A 2 month baby presents with history of jaundice, turmeric colored urine and pale stools since bih. Examination reveals liver span of 10 cms, firm in consistency and spleen of 3 cms. The most specific investigation for establishing the diagnosis would be:Liver function testsUltrasound abdomenPeroperative cholangiogramLiver biopsy  <response>: All patients suspected of having biliary atresia should undergo exploratory laprotomy and direct cholangiography to determine the presence and site of obstruction. Ref: Kliegman, Behrman, Jenson, Stanton 2008, Chapter 353, Cholestasis, In the book, NELSON TEXTBOOK OF PEDIATRICS, Volume 2, 18th Edition, New Delhi, Page 1673; Harrisons Internal Medicine, 18th Edition, Page 2624. 