How do I know if I really need a liver biopsy?

Definitive answer . A biopsy (liver or other organ or tissue) provides your doctor with a near definitive answer to an abnormal finding. This is most commonly needed when a mass or tumor is found where we need to determine cancer vs. Benign. Biopsies are also done to determine the function of an organ, such as one with possible liver disease (cirrhosis, fatty liver, liver failure, etc.) discuss this with your doc.