Transrectal Ultrasound (TRUS)

A transrectal Ultrasound uses sound waves to create an image of the inside the body. It is often used to examine the male pelvic organs. The most common use of ultrasound is to view the prostate gland and screen for prostate cancer.

It is 5-15 minutes outpatient procedure. A small lubricated probe is placed into the rectum this releases sound waves, which creates echoes as they enter the prostate. The echoes that bounce back are sent to the computer which translates the patterns of echoes into a picture of prostate. TRUS is a painless procedure. It is used to feel some tumors in the prostate gland that cannot be detected by DRE. In addition it also helps the doctor to estimate the size of the prostate gland and get a better idea of the PSA density, which helps distinguish BPH from prostate cancer.

Preparation for TRUS:

Prior to TRUS the patient may be asked to have an enema to remove feces and gas from the rectum that might impede the progress of the rectal probe.

TRUS Technique:

The patient traditionally lies on his left side, which is considered a more relaxing position as well allows the easy insertion of the rectal probe. After the probe is inserted into the rectum, the tester adjusts the console on the ultrasound machine to a baseline for the echoes of the normal prostate tissues, which will serve as a standard by which other tissues will be classified. Imaging is usually begun at the base of the bladder and then the probe is rotated to provide a full picture of the prostate.

The rectal probe that sends sound waves to the prostate gland helps bounce back echoes from both normal and abnormal tissues that are relayed on the computer.

  • Isoechoic areas, which represent normal tissue echo the same amount of sound waves as they received.
  • Hypo echoic areas sent back lesser echoes than they have received, indicating the presence of cancer.
  • Hyper echoic areas sent back significantly more echoes than they received indicating the presence of prostatic calcifications or tiny stones in the prostate. They are harmless unless infected.
  • PSA DENSITY, the blood PSA level divided by the size of the prostate as determined by TRUS helps in distinguishing between BPH and prostate cancer.