Medical Content Created by the Faculty of the
Harvard Medical School
In most cases, you lie on your side with your knees bent up to your chest. An ultrasound machine's sensor — a short rod about the width around of two fingers — is covered with a condom and clear jelly and gently inserted into your rectum. You may feel some pressure similar to the sensation before a bowel movement. Once the sensor is in place, an image of your prostate appears on a video screen.
The ultrasound sensor surveys the whole prostate gland and pinpoints specific areas for biopsy. Then the doctor may remove this ultrasound sensor and replace it with a slightly smaller one. In addition to generating an ultrasound image, the smaller sensor has a small tube on its side called a needle guide. Your doctor points the needle guide at specific parts of your prostate. The guide releases a spring-loaded needle to take biopsies from different parts of the prostate. The spring-loading allows this needle to move into and out of the prostate very quickly. You are likely to feel some discomfort from each biopsy, but because the needle moves so quickly, any pain lasts only for a second at a time. Doctors usually collect multiple samples. Your doctor will probably give you antibiotics at the end of this procedure to prevent infection.