(Prostate - Rectal Sonography)
What is a prostate/rectal sonogram?
A prostate/rectal sonogram 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. A sonogram uses ultrasound technology to allow quick visualization of the prostate and related structures from outside the body.
A prostate/rectal sonogram uses a handheld probe called a transducer that sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on the skin at certain locations and angles, the ultrasonic sound waves move through the skin and other 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, clear, water-based gel is applied to the skin to allow for smooth movement of the transducer over the skin and to eliminate air between the skin and the transducer.
By using an additional mode of ultrasound technology during an ultrasound procedure, blood flow to the prostate gland can be assessed. An ultrasound transducer capable of assessing blood flow contains a Doppler probe. The Doppler probe within the transducer evaluates the velocity and direction of blood flow in a blood vessel by making the sound waves audible. The degree of loudness of the audible sound waves indicates the rate of blood flow within a blood vessel. Absence or faintness of these sounds may indicate an obstruction of blood flow.
Related procedures that may be performed to evaluate the prostate gland and rectum include prostate biopsy and sigmoidoscopy. Please see these procedures for more information.
What is the prostate gland?
The prostate gland is about the size of a walnut 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 prostate/rectal sonogram 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. Prostate/rectal sonography may be used to stage rectal cancer, monitor the treatment of rectal cancer, and to assess the rectum for other problems.
A prostate/rectal sonogram 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.
This procedure may also be used to assess blood flow to the prostate or other masses that may be located during the procedure.
There may be other reasons for your physician to recommend a prostate/rectal sonogram.
Risks of the Procedure
There is no radiation used and generally no discomfort from the application of the ultrasound transducer to the skin.