**4. Indications for liver transplantation**

Many patients with worsening ALF or ACLF are eligible for orthotopic liver transplant. Indications for transplant are numerous and include acquired or congenital etiologies, viral hepatitis, drug-induced ALF, cirrhosis, cholestatic diseases, metabolic disorders, vascular derangements, and hepatocellular carcinoma. Because the supply of donor grafts is exceeded by the demand for transplantation, organ allocation is critical. The process of organ allocation is defined by country-specific donor and recipient allocation schemes.

Several models for prognostic data in ALF have been proposed. Consensus exists in the belief that the degree and clinical trend of coagulopathy and hepatic encephalopathy remain the most important prognostic indicators, and are helpful in determining patient appropriateness for transplantation listing. ALF may resolve with supportive treatment, but frequently progresses to death in the absence of transplantation. Patients with ALF therefore have highest priority for liver transplantation.

Patients with decompensated cirrhosis are classified by the Model For End Stage Liver Disease (MELD) score (*Murray and Carithers, 2005*), which has largely replaced the Childs Pugh system, with higher MELD scores indicating higher mortality. Although exceptions are made, including for hepatocellular carcinoma, a MELD score of 15 or higher is generally required to list patients with end stage liver disease for transplantation.

Several contraindications for transplantation exist. Active alcohol or substance abuse, medical non-adherence, poor social support, extrahepatic malignancy, significant cardiopulmonary disease, uncontrolled sepsis, extrahepatic systemic infections, and uncontrolled psychiatric illness are examples of contraindications to liver transplantation.
