The purpose of a prostate biopsy is to determine whether a lump found in the prostate gland is cancerous. If a high level of prostate-specific antigen, or PSA, is found in the blood, a prostate biopsy may also be used as a diagnostic procedure to determine the cause.
There are several types of prostate biopsies. The most common procedure is called a transrectal biopsy, in which a thin needle is inserted through the rectum in order to gather tissue from the prostate for testing. In other cases, the needle can be inserted through the urethra or through the perineum, which is the area between the anus and scrotum. The tissue samples taken during the biopsy are closely examined under a microscope for cancer cells.