If prostate cancer is suspected, your doctor may recommend a transrectal ultrasound.

In this procedure, the doctor or technician inserts a probe slightly larger than a pen into your rectum. The probe directs high-frequency sound waves at the prostate, and the echo patterns form an image of the gland on a television monitor. The image shows how big the prostate is and whether there are any irregularities, but cannot definitively identify tumors.

TRUS may also be used to obtain a biopsy where the doctor guides a needle to the correct spot in the prostate gland to collect a tissue sample.