A sonogram is a diagnostic procedure that uses sound waves to create images of the internal structures of the body. In men, it may be used to examine the size, shape and condition of the prostate gland (located below the bladder) and rectum (the last region of the intestine), as well as blood flow through these structures. The images are processed by a computer and may be viewed on a monitor.
A prostate/rectal sonogram may be indicated to evaluate the prostate for abnormalities such as enlargement, obstruction of urine and cancer, as well as rectal abnormalities. It guides your doctor while obtaining a tissue sample (biopsy) or placing a radiation seed to treat prostate cancer and can also be used to assess the effectiveness of treatment.
Before the procedure, your bowels need to be emptied. You will lie on your left side with your knees bent towards your chest. A device known as a transducer is lubricated with a gel and inserted into your rectum. It is gently rotated to get a clear view. High-frequency sound waves are produced by the transducer. They bounce off the structures of the prostate and rectum and are picked up and processed to create images. A special transducer producing audible sound waves may be used to assess the direction and flow of blood. Once imaging is complete, the transducer is removed, and the gel wiped off; following which you may resume your normal activities.
The sound waves used are harmless and the procedure is not associated with any significant risks other than some discomfort produced by the insertion of the transducer.