This test is useful in guiding needle biopsy of the prostate for the diagnosing for prostate cancer. Trans-rectal ultrasonography (TRUS) is a helpful diagnostic that helps in the early detection of prostate cancer. It uses sound waves to produce an image of the prostate gland. It also allows and accurate measurement of the size of the prostate that can help guide treatment of BPH or benign (non-cancerous) enlargement of the prostate which can cause difficulty urinating. TRUS can also be a helpful tool in the evaluation of male infertility. TRUS can identify findings suggestive of a blockage of the male reproductive tract that may be correctable. Ultrasound is safe, noninvasive, and does not use ionizing radiation.