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Transrectal Ultrasound - Uses, Preparation, Procedure, and Limitations

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Transrectal ultrasound is an imaging technique used to look at abnormalities in the prostate. Read this article to learn more about transrectal ultrasound.

Written by

Dr. Narmatha. A

Medically reviewed by

Dr. J. N. Naidu

Published At December 29, 2022
Reviewed AtDecember 29, 2022


Transrectal ultrasound (TRUS) is used to detect diseases of the prostate. It is also called a prostate sonogram or endorectal ultrasound. It is often used in the diagnosis of prostate cancer. Prostate cancer is the second most cause of death from cancer in men in the United States. The prostate (a male reproductive organ) includes the penis, seminal vesicles, and testicles. The function of the prostate gland is to produce seminal fluid. The prostate is located below the urinary bladder and in front of the rectum, which is the end portion of the large intestine.

What Is an Ultrasound?

Ultrasound is a diagnostic tool that captures pictures of organs inside the human body by passing high-frequency sound waves. The other term for ultrasound imaging is sonogram. While performing ultrasound, a transducer, which is a hand-held probe, generates sound waves with a higher frequency that reach the organs, which bounce back and are received by the transducer. The transducer receives the reflected waves, which are then converted by the computer into images of the organs. It has the ability to show the structure and movement of the internal structures. It can also show blood flowing through the blood vessels.

What Are the Uses of Transrectal Ultrasound?

Transrectal ultrasound is useful in the following conditions:

  • To detect prostatitis (swelling of the prostate gland).

  • To detect prostate cancer (abnormal mass within the prostate).

  • Find the cause of infertility in men.

  • Diagnosis of benign prostatic hyperplasia (BPH) [a noncancerous condition in which the prostate gland is enlarged].

  • Determine the size of the prostate gland.

  • Determine whether prostate cancer has spread to lymph nodes or other body parts.

  • Guiding tool in the biopsy.

It is also useful in the diagnosis of the following symptoms:

  • Presence of nodule in the prostate, which is felt during physical examination.

  • High PSA (prostatic-specific antigen) level in the blood.

  • Symptoms of prostate cancer include:

  • Pain or difficulty in urination.

  • Pain while ejaculating.

  • Blood in the urine or semen.

  • Increase in frequency of urination.

How to Prepare for a Transrectal Ultrasound?

  • Refrain from taking antiplatelet medicine (drugs that prevent platelet aggregation) or blood thinners such as Aspirin for about seven to ten days before the procedure if a biopsy is advised.

  • An enema may be administered before the procedure (a medicine used to clean the bowel).

  • Emptying the bladder before the scan.

  • Have a light meal before the procedure.

How Is the Transrectal Ultrasound (TRUS) Performed?

  • For transrectal ultrasounds, patients are instructed to undress below their waist and asked to lie on their side (decubitus position) with their knees bent on the procedure table. A disposable cover is placed over the transducer, which is lubricated with a gel to make the insertion easy and painless.

  • This procedure uses a long transducer to produce sound waves at a frequency of about 8 to 10 MHz. Modern transducers have frequencies in the range of 5 to 10 MHz (megahertz).

  • The doctor may inspect the anus and perineal area (space between the anus and scrotum) before inserting the transducer for any hindrances such as hemorrhoids (inflammation of the rectal veins), skin problems, or anal issues. They bring the transducer slowly through the anus. Patients may feel slight pressure, but it is painless.

  • Images are taken from different angles to get better images. Images of the prostate and the surrounding tissues will appear on the screen.

  • After the procedure, patients may see a small amount of blood in the urine or semen. This procedure is completed within 20 minutes.

What Are the Factors to Be Considered in the Screening of Prostate Cancer?

Transrectal ultrasound is an effective screening tool for prostate cancer. Screening for prostate cancer depends on the following factors such as age, level of risk, and family history. The screening test is needed in people with a high risk of prostate cancer. The common risk factors are positive family history, abnormal digital rectal examination (DRE), and increased PSA level. Black African and Caribbean men have an increased risk of prostate cancer than white men. Men aged between 55 to 69 have greater benefits from screening. PSA screening is not advised for men aged above 70 years.

How Is the Transrectal Guided Prostate Biopsy Done?

Prostate biopsy is recommended in patients having the symptoms of prostate cancer and increased PSA (prostatic-specific antigen) levels. According to the American Cancer Society, patients having PSA levels greater than ten have an increased risk of prostate cancer by more than 50 percent. During this procedure, the doctor injects local anesthesia into the prostate. Under the guidance of transrectal ultrasound, the doctor uses a thin needle that will be placed through the rectum into the prostate. This needle collects the tissue samples from the prostate gland, which will be viewed later under a microscope. This procedure is called transrectal guided core needle biopsy. As there might be a chance of infection with the biopsy procedure, the patient is instructed to take antibiotics before and after the procedure. Even though the ultrasound detects abnormalities in the prostate, sometimes the biopsy results are shown normally. In such conditions, the patients are asked to repeat this procedure six to 12 months after the previous scan.

What Are the Interpretations of Transrectal Ultrasound (TRUS)?

The rectal ultrasound produces sound waves and sends them to the prostate gland. The normal and abnormal tissue sends back different kinds of echoes. These echoes are processed in the computer, which translates them into a video picture of the prostate.

  • Isoechoic Zones - Areas of normal tissue will bounce back the same amount of sound waves which they received.

  • Hypoechoic Zones - Hypoechoic areas will send back only fewer echoes than they received and often indicate the presence of cancer.

  • Hyperechoic Zones - Hyperechoic areas will send back considerably more echoes than they received which indicates the presence of prostatic calcifications or stones in the prostate. The stones are harmless unless infected.

What Is the Limitation of Transrectal Ultrasound?

Transrectal ultrasound cannot be performed in patients who underwent surgery to remove their rectum because this procedure places the transducer through the rectum. In such conditions, regular ultrasound or magnetic resonance imaging (MRI) of the pelvis may be recommended.


Transrectal ultrasound (TRUS) can help in the early diagnosis of prostate cancer. It is often used as a guiding tool in the treatment of prostate cancer, such as brachytherapy (a type of radiation therapy used in cancer treatment) and cryotherapy (a procedure that kills cancer cells using freezing cold). Transrectal ultrasound is a cost-effective imaging tool that does not use ionizing radiation. It gives an accurate picture of soft tissues than X-ray images. This procedure does not require hospitalization.

Frequently Asked Questions


How to Prepare for a Transrectal Ultrasound?

Before a transrectal ultrasound, the provider will take a complete history of the patient regarding any medications or allergies. After that, the patient may be asked to have an enema one to four hours before the transrectal ultrasound. The enema will help in clearing out the colon and rectum. Additionally, the patient may be asked to urinate to empty the bladder before the procedure.


How Much Does Transrectal Ultrasound Cost?

The cost of ultrasound can vary from region to region. In India, it ranges from 800 to 1000 rupees in major cities. The lowest price of prostate ultrasound has been found to be lowest in Delhi. However, the price can be as much higher upto 3000 rupees. In other countries like the USA, it can be expensive compared to India, where it may cost between $100 - $1,000 (₹ 8000 to ₹ 80,000).


How Long Does Transrectal Ultrasound Take?

Transrectal ultrasound normal is a 15 to 30-minute procedure. This is usually done in a doctor’s office, clinic, or hospital, and the patient can go home on the same day. In this procedure, sound waves create an image of the prostate gland.


How Is a Transrectal Ultrasound Done?

In transrectal ultrasound, the patient is asked to lay on their side and bend the knees towards the chest. After that, a lubricated probe is inserted into the rectum. The probe is about the size of a finger, sending out high-energy sound waves that bounce off internal tissues or organs and make echoes. The echoes form a picture of the tissue called a sonogram.


Is Transrectal Ultrasound Painful?

Transrectal ultrasound usually does not cause any pain. However, it can be uncomfortable sometimes. The side effects of transrectal ultrasound are very rare and only can cause some minor discomfort which might include rectal bleeding or pain, which is a rare sight. For any discomfort or pain, local anesthesia can be used.


What Is the Purpose of Transrectal Ultrasound?

Transrectal ultrasound (TRUS) is usually done to diagnose prostate conditions. This procedure can diagnose abnormalities related to the rectum and prostate. Moreover, it helps in taking the tissue from the prostate and examining it to understand the actual cause of the problem. Therefore, transrectal ultrasound can also helps in treating prostate conditions and can also help in diagnosing conditions related to reproductive organs


What Can a Transrectal Ultrasound Detect?

The transrectal ultrasound may also be used to collect the tissue sample from the rectum, which can further be examined to detect the following conditions, which include -
 - Enlarged prostate (benign prostatic hyperplasia).
 - Inflamed prostate (prostatitis).
 - Prostate cancer.
 - Cysts of reproductive organs.
 - Problem with the reproductive system in females.
 - Infertility in females.
 - Rectal and anal cancer.


What Is a Transrectal Ultrasound Biopsy of the Prostate?

Transrectal ultrasound biopsy of the prostate is a procedure in which a tissue sample is taken from the prostate using a thin needle called a needle biopsy. The needle is inserted through the rectum and into the prostate, and the sample is collected. The transrectal ultrasound helps in guiding the needle. After that, the sample is examined under the microscope to check for conditions like cancer or enlarged prostate.


How Accurate Is Transrectal Ultrasound?

According to various research, it has been found that transrectal ultrasound is highly accurate. It helps in the detection of any abnormalities in the rectal as well as with the prostate gland. The images viewed by the ultrasound are of high quality, and any abnormalities can be easily visible. Moreover, a needle biopsy can also be done along with this, which helps detect prostate cancer.
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Dr. J. N. Naidu
Dr. J. N. Naidu

General Practitioner


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