An abnormal age-adjusted prostate specific antigen (PSA) test or abnormal digital rectal (DRE) exam should be followed by a biopsy of the prostate cells to determine whether they are in fact cancerous. A biopsy is a procedure in which a sample of tissue is taken from the prostate and then viewed under a microscope to check for abnormalities. In some patients a high normal or borderline PSA may also warrant a biopsy, especially if it is accompanied by changes in urinary or sexual function. Occasionally, patients with extremely elevated PSA also report bone pain and have abnormal bone X-rays indicating extra bone growth, or osteoblastic metastases. This situation also requires a biopsy of the prostate.

Before the biopsy, the doctor will prescribe antibiotics to reduce the risk of infection. The biopsy itself is performed by a urologist on an outpatient basis and usually takes a little more than half an hour. After the patient receives an enema and the area is numbed, a transrectal ultrasound (TRUS) probe is inserted into the rectum. The TRUS allows the urologist to view the prostate. A fine-gauge biopsy needle is then used to remove several samples of tissue from various areas of the prostate gland. The tissue samples are then sent to the lab for analysis. Although the procedure may cause some discomfort or pain, the process is generally well tolerated. For a few days after the procedure, the patient may feel sore and notice blood in the urine and light bleeding from the rectum.

It should be noted that biopsies can sometimes miss the cancer if none of the biopsy needles pass through it. This is known as a false-negative result. If your doctor still suspects prostate cancer, he may ask you to repeat the biopsy procedure. Your doctor may also use other diagnostic tools, such as ultrasonography.