Fulminant hepatitis is the most feared complication of viral hepatitis: acute liver failure with massive hepatocyte (liver cell) necrosis, produced when the immune attack on infected cells becomes overwhelming. It occurs mostly with HBV, HDV and HEV (the viruses of hepatitis B, D and E), and up to 50% of all cases of fulminant hepatitis are due to HBV infection. HCV (hepatitis C virus) almost never causes it. HEV usually does not either, but it can occur in about 1% of HEV cases, and the risk is far higher in pregnancy, where it affects up to 20% of pregnant women. HAV (hepatitis A virus) causes fulminant hepatitis only rarely — in older adults with underlying chronic liver disease such as chronic HBV or HCV, and mostly in elderly or immunosuppressed patients.
Recognising fulminant hepatitis
Fulminant hepatitis is recognised by a characteristic set of findings that reflect failing liver function. Hepatic encephalopathy, a disturbance of brain function caused by liver failure, mostly progresses to coma. The liver becomes extensively small and shrunken, with lowered ALT and AST (the liver enzymes) and a rapidly rising bilirubin. The prothrombin time (PT), a clotting test, is extensively prolonged, and ascites (fluid in the abdomen) and oedema are present.
The terminal events are brainstem compression, gastrointestinal bleeding, sepsis, cardiovascular collapse and renal failure, and the mortality is as high as 80%.
Rarer complications
Viral hepatitis can also be complicated, more rarely, by pancreatitis, myocarditis, aplastic anaemia, atypical pneumonia and peripheral neuropathy. Since a hepatitis-like illness with raised aminotransferases is not always viral, the next question is what else can produce it.