Liver biopsies may be taken percutaneously (via a needle through the skin), transvenously (through the blood vessels) or directly during abdominal surgery. The sample is examined by microscope, and may be processed further by immunohistochemistry, determination of iron and copper content, and microbiological culture if tuberculosis is suspected
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. 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).
If the diagnosis is already clear, such as chronic hepatitis B or hepatitis C, liver biopsy is useful to assess the severity of the associated liver damage. The same is true for haemochromatosis (iron overload), although it is frequently omitted. Primary biliary cirrhosis and primary sclerosing cholangitis may require biopsy, although other diagnostic modalities have made this less necessary.
Occasionally, liver biopsy is required to monitor the progress of treatment, such as in chronic viral hepatitis.