Liver biopsy is often required for the diagnosis of a liver problem (jaundice, abnormal blood tests) where blood tests, such as hepatitis A serology, have not been able to identify a cause. It is also required if hepatitis is possibly the result of medication, but the exact nature of the reaction is unclear. Alcoholic liver disease and tuberculosis of the liver may be diagnosed through biopsy.[1] Direct biopsy of tumors of the liver may aid the diagnosis, although this may be avoided if the source is clear (e.g. spread from previously known colorectal cancer).[1]