Acute liver failure: Viva

Branch 1: Diagnosis and the paediatric definition

The candidate should recognise that this boy has acute liver failure. The combination of an international normalised ratio of 3.8 with borderline drowsiness, in a previously well adolescent without known chronic liver disease, meets the paediatric definition, and the low ceruloplasmin and Kayser-Fleischer rings make Wilson disease the leading cause. A strong candidate states the definition precisely: an international normalised ratio of 1.5 or greater with any hepatic encephalopathy, or 2.0 or greater without encephalopathy, in a child without chronic liver disease. [1]

The candidate should emphasise the key paediatric distinction that hepatic encephalopathy is not required for the diagnosis, unlike in adults, because infants and young children may not show recognisable encephalopathy until late. In this adolescent the borderline drowsiness is early encephalopathy, but even without it the international normalised ratio of 3.8 alone would confirm the diagnosis. The candidate should also distinguish this from acute-on-chronic failure: although Wilson disease is a chronic condition, this presentation is an acute decompensation in a previously undiagnosed child, which is a classic acute liver failure scenario rather than acute-on-chronic failure of a known disease. [1]

If the examiner presses on Wilson disease, the candidate should describe the nearly pathognomonic combination of Coombs-negative haemolytic anaemia, a low or normal alkaline phosphatase relative to the bilirubin, and acute liver failure, often with Kayser-Fleischer rings on slit-lamp examination. The low alkaline phosphatase-to-bilirubin ratio is a bedside clue, and a 24-hour urinary copper or a serum free copper level confirms the diagnosis. [2]

Branch 2: Immediate management and empirical N-acetylcysteine

If asked about immediate management, the candidate should describe resuscitation in parallel with the workup and early referral to a transplant centre. The airway, breathing, and circulation are stabilised, with intubation for grade three or four encephalopathy. A bedside glucose is checked and hypoglycaemia treated with a continuous dextrose infusion, because the failing liver cannot perform gluconeogenesis. The candidate should explain the restrained approach to coagulopathy: the international normalised ratio is the key prognostic trend, so fresh frozen plasma is reserved for active bleeding or procedures, not given prophylactically, and vitamin K is administered. [1]

A strong candidate starts N-acetylcysteine early and empirically. The candidate should give the dose precisely: a loading dose of 150 milligrams per kilogram over 60 minutes, then 50 milligrams per kilogram over 4 hours, then 100 milligrams per kilogram over 16 hours, for a total of 300 milligrams per kilogram over 21 hours. The candidate should justify its use beyond acetaminophen: the adult randomised trial showed improved transplant-free survival in early-stage non-acetaminophen acute liver failure, and the NASPGHAN position paper supports it for children with non-acetaminophen acute liver failure and coagulopathy. The candidate should mention monitoring for anaphylactoid reactions, most common with the loading dose. [1]

The candidate should address Wilson disease specifically. Chelation therapy with penicillamine or zinc is started, but the candidate should state honestly that Wilson disease presenting as acute liver failure usually requires transplantation because the hepatic injury is often irreversible by presentation. The workup for a live donor within the family may begin in parallel, but the listing decision rests on the trajectory. [2]

Branch 3: The transplant decision and King's College Criteria

If the examiner moves to transplantation, the candidate should explain that liver transplantation is the definitive treatment for acute liver failure that progresses despite maximal medical therapy, and that the decision to list is the most consequential judgement. The candidate should track the trend in the international normalised ratio, the depth and progression of encephalopathy, the arterial pH and lactate, and the development of multiorgan dysfunction, and describe a child who is worsening on maximal medical therapy as the one to list urgently. [1]

The candidate must address the King's College Criteria explicitly. These were developed by O'Grady in 1989 for adult fulminant hepatic failure and use an arterial pH below 7.3 or a composite of international normalised ratio, creatinine, and encephalopathy for paracetamol cases, and the international normalised ratio or a composite of age, bilirubin, cause, and jaundice duration for non-paracetamol cases. The candidate should state clearly that these criteria are not validated in children and perform poorly in paediatric cohorts, so paediatric transplant decisions rely on dynamic trends, not the adult score. Applying the adult score rigidly to children risks both denying transplant to a deteriorating child and listing a child who is actually recovering. [3]

A strong candidate closes with the operational priorities: early referral to a transplant centre before multiorgan failure is established, because transfer after decompensation is often too late; a multidisciplinary decision involving hepatology, intensive care, and transplant surgery; and the consideration of live donor liver transplantation where a suitable donor is identified. The candidate should communicate the gravity honestly to the family while reassuring them that modern intensive care and transplantation have transformed the outlook for many children who would once not have survived. [1]