Ultrasound Imaging

An ultrasound examination, also commonly referred to as a sonogram, is a painless, diagnostic technique that makes use of the behavior of sound waves in the human body. When these sound waves are transmitted into the body, they are reflected in specific ways by specific tissues and organs. These reflected waves can be used to produce images of internal organs without the pain or exposure to radiation.

Depending on the reason for the study and the circumstances, ultrasound imaging may be performed in the urologist's office, in the hospital or in an outpatient facility.

In most cases, very little preparation is needed for an ultrasound examination. Some examinations, such as a bladder scan for residual urine, require limited experience while others, such as ultrasound examinations of the kidneys, testicles or prostate, require more experience or expertise.

The patient will be asked to lie down on the examination table. A clear, water-based gel is applied to the skin over the area to be examined. This gel helps with the transmission of the sound waves. A transducer, which is a hand-held probe, is then moved over that area. Prostate ultrasound examinations are performed by placing a specially designed probe into the rectum.

There is no risk of radiation with this study and the patient can resume their daily activities immediately following this test.

What can be expected with a bladder ultrasound?

The bladder is an organ made of smooth muscle that stores urine until ready for release. The most common reason for bladder ultrasound is to assess bladder emptying by measuring residual urine after urination. Many conditions may result in disorders of bladder emptying and these include an enlarged prostate, urethral stricture or bladder dysfunction. Bladder ultrasound may also provide information about the bladder muscle, the presence of diverticula of the bladder, the size and shape of the prostate, the presence of stones or large tumors in the bladder. Bladder ultrasound as performed for urologic purposes usually does not assess the ovaries, uterus or colon.

Bladder ultrasound does not require fasting or bowel preparation. The patient should not empty their bladder prior to arriving at the physician's office for a full bladder is useful for the examination.

The examination is performed with the patient lying on his/her back on the examination table. A conducting gel is placed on the skin to facilitate transmission of the sound waves. The transducer is placed on the lower abdomen between the umbilicus and the pubic bone. The image is viewed on a monitor and interpreted in real time.

What can be expected with a kidney ultrasound?

The kidneys are fist-sized organs located in the retroperitoneum — the space behind the intestines and other abdominal organs. They are responsible for cleansing the blood of waste products and producing urine. They also balance electrolytes in the body, such as sodium and potassium, while providing hormones necessary to regulate blood pressure and red blood cell production.

There may be many indications for a renal ultrasound examination. Renal ultrasound studies are useful for demonstrating the size and position of the kidneys and are helpful in identifying obstruction of the kidney, kidney stones or masses in the kidney.

Renal ultrasound does not require fasting, bowel preparation or a full bladder. The test is performed with the patient lying on their back on the examination table and a conducting gel is placed on the skin to facilitate transmission of the sound waves. The right kidney is imaged by placing the transducer over the right upper abdomen and evaluation of the left kidney may require having the patient roll toward the right to expose the left flank.

What can be expected with a scrotum ultrasound?

The testicles (testes) are contained in a skin-covered muscular sac called the scrotum. The testicles manufacture sperm cells for reproduction and also produce testosterone. The primary indication for scrotal ultrasound is the evaluation of masses in the scrotum or in the testes themselves. The most common mass in the scrotum is a benign collection of fluid around the testis called a hydrocele. Another common condition is a collection of fluid in the epididymis called a spermatocele. Ultrasound studies are also very helpful in investigating solid masses within the testes, which may represent testicular cancer.

A scrotal ultrasound examination does not require fasting, bowel preparation or a full bladder. The test is performed with the patient lying on his back. The scrotum is elevated on a towel and warm gel is applied to the scrotum to help conduct the sound waves.

What can be expected with a prostate ultrasound and biopsy?

The prostate is located at the base of the bladder and encircles the urethra like a napkin ring. The prostate provides a portion of ejaculatory fluid, which is important for reproduction. Enlargement of the prostate may cause obstruction of the bladder. The most common indication for a prostate ultrasound (also known as a transrectal ultrasound) is to evaluate men considered at risk for prostate cancer (see prostate cancer screening). Because early prostate cancer cannot be reliably diagnosed by the ultrasound appearance of the prostate alone, the study is usually performed in association with a simultaneous prostate biopsy (see biopsy).

Another common indication for ultrasound is obtaining the volume or size of the prostate for treatment planning purposes. Patients being considered for radioactive seed implantation to treat prostate cancer (brachytherapy) undergo transrectal ultrasound of the prostate to determine prostatic volume. This is necessary to plan the distribution and number of radioactive seeds needed for treatment of the tumor. Transrectal ultrasound may also be performed when transurethral resection of the prostate or thermal therapies of the prostate are planned. Finally, the study is used to determine prostate specific antigen density.

The patient may be asked to use an enema prior to the procedure to better facilitate an adequate examination. The procedure is performed with the patient lying on his side on the examination table.

The ultrasound probe (transducer) is inserted into the rectum to obtain the image of the prostate. Local anesthesia may or may not be used when performing a biopsy. After measuring the prostate volume and identifying any suspicious areas, biopsies are obtained by inserting a special needle through a channel on the transducer. The needle is inserted and the biopsy is obtained quickly. The number of biopsy "cores" obtained is variable but averages six to eight.

The procedure requires 10 to 20 minutes and the main risks are infection and bleeding from the rectum or bladder. Patients are asked to refrain from heavy physical activity for 24 to 48 hours after the procedure. Oral antibiotics are administered prior to and after the biopsy to reduce the likelihood of infection. Some patients may notice blood in their ejaculate for several weeks after the procedure. This is common and not a cause for concern.

Results of the biopsy often take several days. It is important for patients to discuss the results of the biopsy with their urologist. If cancer is diagnosed, a discussion of treatment options is needed. If the biopsy shows no cancer, a strategy for follow up will be discussed. The pathologist may report a precancerous condition on the biopsy that may prompt more frequent follow up or even repeat biopsy.

What are some additional uses of urologic ultrasound?

Evaluation of infertility: Under some circumstances, transrectal ultrasound may be useful in demonstrating the presence of abnormalities of the seminal vesicles and prostate. Examination of the testes may also be of value.

Evaluation of the female urethra: Transvaginal ultrasound may be useful in demonstrating a urethral diverticulum. A urethral diverticulum may be associated with urethral pain and recurrent urinary tract infection.

Pediatric urology: The painless and noninvasive nature of ultrasound and the immediacy of the results make it ideal for working with children. Ultrasound is particularly well suited to pediatric patients. Ultrasound provides excellent images of the kidneys and bladder. It is useful in the evaluation of congenital abnormalities of the urinary tract, the evaluation of problems with urination and the workup of recurrent urinary tract infections.

Evaluation of voiding dysfunction: Ultrasound may provide invaluable information about the function of the bladder neck and its relationship to urinary incontinence in men and women.

Evaluation of blood flow: A Doppler ultrasound may be used to determine blood flow in urologic organs especially the testes and kidneys.