If the results from a man’s digital rectal exam (DRE), prostate-specific antigen (PSA) test, or both suggest prostate cancer may be present, transrectal ultrasound is performed to determine the size of the prostate, to identify any areas that are suspicious for cancer, and to direct the needles used for prostate biopsy. A prostate biopsy typically takes about 15 to 20 minutes and is performed on an outpatient basis.
Doctors routinely use a local anesthetic such as lidocaine (Xylocaine) to reduce discomfort during the procedure. The ultrasound examination is performed with the man lying on his side. An ultrasound probe (about the size of a finger) is gently inserted 3 to 4 inches into the rectum. The probe emits soundwaves that are converted into images corresponding to the different prostate zones. Small prostate cancers are usually not detectable by ultrasound examination. Fitted to the probe is a biopsy gun with a needle that is fired through the wall of the rectum. The needle extracts small pieces of prostate tissue in less than a second. Ideally, at least 10 to 12 tissue samples (“cores”) are taken from the prostate. A pathologist examines the samples under a microscope to determine whether cancer is present.
If the prostate biopsy shows no cancer but the physician still suspects that cancer is present because of an abnormality on the DRE or PSA test, a repeat biopsy may be performed. Each year, about 1 million prostate biopsies are performed in the United States, and of those, about one in three are cancerous.
A prostate biopsy usually causes only minor discomfort. Common side effects include minor rectal bleeding; blood in the stool, urine, or semen; and soreness in the biopsied area. All of these side effects resolve over time.