If acute viral hepatitis is suspected, the following tests are done to screen for hepatitis viruses A, B, and C: IgM antibody to HAV (IgM anti-HAV) Hepatitis B surface antigen (HBsAg) IgM antibody to hepatitis B core (IgM anti-HBc) Antibody to hepatitis C virus (anti-HCV) and hepatitis C RNA (HCV-RNA) If the IgM anti-HAV test is positive, acute hepatitis A is diagnosed.