Acute severe hepatitis: Acute hepatitis with acute onset, extreme malaise, obvious gastrointestinal symptoms, severe jaundice, and rapid onset of hepatic encephalopathy of degree II or higher (classified as degree IV), prothrombin activity (PTA) below 40% within 2 weeks, and other causes excluded. In addition, the disease should be considered in those with progressive narrowing of the hepatic turbid cirri, rapid deepening of jaundice, or shallow jaundice or even jaundice but with extreme weakness, obvious gastrointestinal symptoms, and rapid onset of hepatic encephalopathy of grade II or higher (grade IV), and prothrombin activity (PTA) of less than 40%.