A prostate biopsy involves taking small pieces of prostate tissue to be looked at under the microscope, to see if there is any prostate cancer. Ultrasound-guided biopsy of the prostate is a procedure that involves removing a small piece of prostate tissue for microscopic examination. An ultrasound probe is inserted into your rectum, using a gel to make it more comfortable. The ultrasound probe scans the prostate and an image appears on a screen. A needle is then inserted through the wall of the rectum into the prostate gland – using the ultrasound image as a guide.