Transrectal ultrasound (TRUS)

A transrectal ultrasound (TRUS) is a procedure used to create images of organs and tissues near the rectum. It's mostly used to look at the prostate. A TRUS can also be used to look at other organs including the seminal vesicles (glands found on each side of the prostate), vagina, rectum and anus.

During a TRUS, a doctor inserts a transducer (also called a probe) into the rectum. The transducer sends high-frequency sound waves through the wall of the rectum and into surrounding organs. A computer analyzes the wave patterns (called echoes) as they bounce off the organs and converts them into an image that doctors view on a video screen.

A transrectal ultrasound (TRUS) may also be called an endorectal ultrasound. Doctors may call it a prostate sonogram when it's used to look at the prostate.

A TRUS is mainly done to help diagnose prostate cancer and other conditions of the prostate. A TRUS is often used if you have a high prostate-specific antigen (PSA) level, the doctor finds an abnormal area during your digital rectal exam (DRE) or you have symptoms, such as trouble urinating.

Your doctor may do this procedure to:

• look for abnormal areas in the prostate
• look at the size and shape of the prostate
• guide a needle during a core biopsy of the prostate (called a TRUS-guided prostate biopsy)

Your doctor may do a TRUS for other reasons. They may use a TRUS to check your reproductive organs for cysts or other abnormalities that are causing fertility problems. A TRUS can also be used to help diagnose and stage cancers in the rectum, anus or other organs.

A TRUS can help deliver treatments for cancer or non-cancerous conditions of the prostate or surrounding structures. A TRUS can be used to:

• place an implant for brachytherapy
• deliver high-intensity focused ultrasound (HIFU), which uses ultrasound waves to create intense heat and destroy tissue
• perform cryosurgery

A TRUS is usually done in a hospital or clinic as an outpatient procedure. This means that you won't have to stay overnight. A TRUS usually takes 15 to 30 minutes.

Your healthcare team will tell you how to prepare for a TRUS. Depending on the organ being looked at, you may need to:

• stop taking certain medicines, including blood thinners (anticoagulants) 7 to 10 days before the test
• have an enema to help clean out the colon and rectum 1 to 4 hours before the test
• urinate (pee) to empty your bladder just before the test

Tell your healthcare team if you have a urinary tract infection (UTI). You may need to wait for the infection to go away before you have a TRUS. Having a TRUS can worsen the UTI and make you more uncomfortable.

You will change into a hospital gown and lie on your side with your knees bent toward your chest. Your doctor will put a protective cover and clear jelly (lubricant) on the transducer, which is about the width of a finger. Your doctor will gently insert it into your rectum. You may feel some pressure or a sense of fullness when the transducer is in place. Once the transducer is inserted, images of your organs and tissues will show up on the screen.

A TRUS-guided prostate biopsy collects samples of tissue or cells from the prostate. It is done after an abnormal area has been found in a previous DRE, TRUS, MRI or other test.

Before the biopsy, your doctor will inject a local anesthetic into your prostate to numb the area. This will reduce pain or discomfort during the biopsy.

Like a typical TRUS, your doctor will insert the transducer into the rectum to look at the prostate. But there will be a thin, hollow needle attached to the transducer. After finding the abnormal area on the ultrasound, your doctor will push the needle through the wall of the rectum into the prostate.

Your doctor uses the needle to collect several samples of tissue (called cores) from different parts of the prostate, including the abnormal area shown on the ultrasound. These samples will be sent to a lab and tested for cancer cells.

There aren’t usually any side effects from the TRUS itself. Side effects happen more often with a TRUS-guided prostate biopsy.

The most common side effect is having blood in your urine, stool (poop) or semen for several days after the procedure. Other side effects include:

• infection
• tenderness and pain
• lower urinary tract symptoms (LUTS) including urinating often, a weak or slow urine stream, or leaking (urinary incontinence)
• painful urination

You may be given antibiotics before and after a TRUS-guided prostate biopsy. Antibiotics can reduce the risk of infection. Tell your healthcare team if you are allergic to any antibiotics or other medicines.

If you develop a fever within a few days of the biopsy, tell your healthcare team right away. This may be a sign of an infection.

For a TRUS used to look at the prostate, an abnormal result may mean you have:

• an enlarged prostate (called benign prostatic hyperplasia)
• an inflamed or infected prostate (called prostatitis)
• prostate cancer

For a TRUS-guided prostate biopsy, if the lab result comes back negative, it means no cancer is found in the sample. But even with many samples collected, it's still possible to have a false-negative result. Your doctor may recommend having an MRI to look for any abnormal areas missed in previous tests. If an abnormal area is found, your doctor may repeat the biopsy.

You may need to have another TRUS-guided prostate biopsy in a few months if:

• the PSA level goes up
• there were precancerous cells in the first biopsy

If the results of the TRUS or TRUS-guided prostate biopsy are abnormal, your doctor may recommend more tests, procedures, follow-up care or treatment.

For a TRUS used to look at organs other than the prostate, your doctor will talk to you about the results and further tests or treatment you may need.