Tests & Procedures



Transrectal Prostate Ultrasound

(Prostate - Rectal Sonography)

Procedure Overview

What is a transrectal prostate ultrasound?

A transrectal prostate ultrasound is a noninvasive (the skin is not pierced) procedure used to assess the size, shape, and location of the prostate gland and to assess the rectum. Ultrasound technology is used to allow quick visualization of the prostate and related structures from outside the body.

A transrectal prostate ultrasound uses a transducer that sends out ultrasonic sound waves at a frequency too high to be heard. The ultrasonic sound waves move through the body tissues to organs and structures within the body. The sound waves bounce off the organs like an echo and return to the transducer. The transducer picks up the reflected waves, which are then converted into an electronic picture of the organs.

Different types of body tissues affect the speed at which sound waves travel. Sound travels the fastest through bone tissue and moves most slowly through air. The speed at which the sound waves are returned to the transducer, as well as how much of the sound wave returns, is translated by the transducer as different types of tissue.

Prior to the procedure, a clear, water-based gel is applied to the probe to allow for smooth placement in the rectum.

Related procedures that may be performed to evaluate the prostate gland include prostate biopsy and sigmoidoscopy. Please see these procedures for more information.

What is the prostate gland?

Illustration of anatomy of male reproductive tract
Click Image to Enlarge

The prostate gland is about the size of a walnut or slightly larger and surrounds the neck of a man’s bladder and urethra - the tube that carries urine from the bladder. It is partly muscular and partly glandular, with ducts opening into the prostatic portion of the urethra. It is made up of three lobes: a center lobe with one lobe on each side.

As part of the male reproductive system, the prostate gland’s primary function is to secrete a slightly alkaline fluid that forms part of the seminal fluid (semen), a fluid that carries sperm. During male climax (orgasm), the muscular glands of the prostate help to propel the prostate fluid, in addition to sperm that was produced in the testicles, into the urethra. The semen then travels through the tip of the penis during ejaculation.

Reasons for the Procedure

A transrectal prostate ultrasound may be used to assess the size, location, and shape of the prostate gland and nearby structures. A sonogram may be used to examine the prostate gland for evidence of cancer. This procedure may be performed after a finding of elevated prostate-specific antigen (PSA) during a blood test.

A transrectal prostate ultrasound may be performed to assist in placement of needles used to biopsy (obtain a tissue sample) the prostate, or to aid in the placement of radiation “seeds” used to treat prostate cancer. The procedure may also be used for cryotherapy (freezing) of prostate cancer.

There may be other reasons for your physician to recommend a transrectal prostate ultrasound.

Risks of the Procedure

There is no radiation used and little discomfort from the placement of the probe.

The sonogram transducer will be covered in a latex condom-like covering prior to insertion into the rectum. Therefore, the test is contraindicated for patients with a latex allergy.

There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.

Excess stool in the rectum may interfere with the results of the test.

Before the Procedure

  • Your physician will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
  • You may be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if something is not clear.
  • Generally, no prior fasting or sedation is required.
  • You may be given a small enema prior to the procedure.
  • Based upon your medical condition, your physician may request other specific preparation.

During the Procedure

A transrectal prostate ultrasound may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your physician's practices.

Generally, a prostate/rectal sonogram follows this process:

  1. You will be asked to remove any clothing, jewelry, or other objects that may interfere with the procedure.
  2. If asked to remove clothing, you will be given a gown to wear.
  3. You will lie on an examination table on your left side with your knees bent up to your chest.
  4. The physician may perform a digital rectal examination before the sonogram procedure.
  5. The transducer will be lubricated with a clear gel and inserted into the rectum. You may experience a feeling of fullness of the rectum at this time.
  6. The transducer will be rotated slightly several times during the procedure in order to obtain adequate visualization of the prostate gland and other structures.

While the transrectal prostate ultrasound procedure itself causes no pain, having to lie still for the length of the procedure may cause slight discomfort and the clear gel will feel cool and wet. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort.

After the Procedure

There is no special type of care required after a prostate/rectal sonogram. You may resume your usual diet and activities unless your physician advises you differently.

Online Resources

The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your physician. Please consult your physician with any questions or concerns you may have regarding your condition.

This page contains links to other Web sites with information about this procedure and related health conditions. We hope you find these sites helpful, but please remember we do not control or endorse the information presented on these Web sites, nor do these sites endorse the information contained here.

American Cancer Society

American College of Radiology

American Society of Nephrology

National Cancer Institute

National Institute of Diabetes and Digestive and Kidney Diseases

National Institutes of Health (NIH)

National Library of Medicine

Last reviewed: 2/9/2010