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What is Ultrasound Imaging?

An ultrasound exam (or "sonogram") is a painless diagnostic technique that makes use of how sound waves travel through the body. When sound waves pass through the body, they bounce off tissues and organs in certain ways. The reflected waves can be used to make images of the organs inside. The sound waves don’t hurt the body, and there’s no radiation.

Ultrasound imaging may be done in the health provider’s office, in the hospital, or in an outpatient facility. The reason for the study and details of the case will help decide where the test should be done.

In most cases, very little needs to be done before an ultrasound exam. The patient lies on the exam table. A clear, water-based gel is put on the skin over the part to be checked. This gel helps the sound waves go through the body. A hand-held probe ("transducer") is then moved over that part. For prostate ultrasound exams, a specially designed probe is inserted into the rectum.

There is no risk of radiation. The patient can return to daily tasks right away after the test.

Some exams, such as a bladder scan for residual urine, don’t call for the user to have a lot of experience. Other exams, such as ultrasound of the kidneys, testicles or prostate, call for the user to have more experience or skill.

Types of Ultrasounds

Male Urinary Tract
Male urinary tract
Medical Illustration Copyright © 2015 Nucleus Medical Media, All rights reserved

Female Urinary Tract
Female urinary tract
Medical Illustration Copyright © 2015 Nucleus Medical Media, All rights reserved

The bladder is an organ made of smooth muscle. It stores urine until it’s released when you go to the bathroom. The most common reason for bladder ultrasound is to check bladder draining. The urine that remains in the bladder after urinating ("post void residual") is measured. If urine remains, there can be a problem like:

Bladder ultrasound can also give information about:

  • The bladder wall
  • Diverticula (pouches) of the bladder
  • Prostate size
  • Stones
  • Large tumors in the bladder

Bladder ultrasound doesn’t check the ovaries, uterus, or colon.

This test doesn’t require fasting or bowel preparation. If you are not checking for post void residuals, a full bladder is needed. You may be asked to drink many glasses of water an hour before the exam.

The exam is done as you lay on your back on the exam table. A gel is spread on the skin to help transmit the sound waves. The transducer is placed between your navel and pubic bone. The image is viewed on a monitor and read on the spot. To check bladder draining, you’ll be asked to void. When you return, the bladder will be imaged again.

Male Urinary Tract
Male urinary tract
Medical Illustration Copyright © 2015 Nucleus Medical Media, All rights reserved

Female Urinary Tract
Female urinary tract
Medical Illustration Copyright © 2015 Nucleus Medical Media, All rights reserved

The kidneys are 2, fist-sized organs found on either side of your mid-section ("retroperitoneum"). The kidneys remove waste from the blood and make urine. They also balance salts ("electrolytes") in the body, such as sodium and potassium. Hormones that control blood pressure and red blood cell production are also made in the kidneys.

Renal ultrasound studies can show the size and position of the kidneys. They can also show if there are:

  • Blockages
  • Stones
  • Tumors

A kidney ultrasound creates images from sound waves that return from the kidney tissue. Many images are collected to understand problems in the kidney.

If your doctor wants to see how blood flows to and from the kidney, Doppler imaging is used. This is an ultrasound method that makes color images from the movement of flowing blood. It shows the flow of blood through the vessels. It provides excellent motion information not available on a standard sonogram.

No need to fast, prepare your bowel, or have a full bladder. The test is done as you lay on your back on the exam table. A gel is spread on the skin to help transmit the sound waves. The kidneys are imaged by placing the transducer over both sides of the upper belly.

A man's testicles (testes) are in a skin-covered muscular sac called the scrotum. The testicles make sperm cells for reproduction. They also make the male hormone, testosterone. The main reason for scrotal ultrasound is to check swelling or pain. It’s also used to check masses in the scrotum or in the testes.

It is common for fluid to collect around the testis. This is called a hydrocele, and is not cancerous. Other things like cysts in the epididymis ("spermatocele") or large veins in the scrotum ("varicocele") may be found. This study can also be used to look at solid masses as a sign of testicular cancer.

Testicular ultrasound is used to evaluate almost all issues in the scrotum, the sac containing the testicles. It can detect patterns from cancer, or if a mass is intratesticular, extratesticular, solid or cystic. It is used for testicular torsion, and problems with blood flow in the testis. It can be used to prevent testicular death.

For this test, Color-Doppler imaging is used. This high-quality color imaging has made testicular ultrasound an accurate and specific test.

This test needs no preparation. It is done as you lay on your back on the exam table. The scrotum is raised onto a towel and warm gel is applied to help transmit sound waves. The transducer is moved over the area to create images.

Male Reproductive System
Male Reproductive System
Medical Illustration Copyright © 2015 Nucleus Medical Media, All rights reserved

The prostate is found at the base of the bladder in men. It circles the urethra like a napkin ring. The prostate makes part of the ejaculatory fluid, which is needed for reproduction. If the prostate gets large, it may block the bladder.

The most common reason for a prostate ultrasound (also called "transrectal ultrasound") is to check men who might be at risk for prostate cancer. Early cancer can’t easily be diagnosed by ultrasound alone. For this reason, a tissue sample ("biopsy") of the prostate is also done.

To diagnose prostate disease, your doctor will want to examine your prostate gland and nearby tissue. Almost 70% of prostate cancer malignancies are found in the outer zone of the prostate, by the rectum.

Prostate ultrasound can measure the volume or size of the prostate to help plan treatment. Patients receiving radioactive seed implantation ("brachytherapy") to treat prostate cancer have transrectal ultrasound for this purpose. It is used to plan the number of seeds needed and where to place them. This test may also be used to plan prostate surgery or other therapy (such as thermal therapies). The study can measure prostate specific antigen density.

Before this test, you may be asked to use an enema. During the test, you will lie on your side or back on the exam table. The ultrasound transducer probe is inserted into the rectum to see the prostate. The probe sends and receives sound waves through the wall of the rectum and into the prostate gland. These sound waves create images for diagnosis. The urologist will look for signs of prostate cancer. At the same time, a small tissue sample may be taken for a biopsy.

Local anesthesia may or may not be used with a biopsy. For a biopsy, a special needle is pushed through a channel on the transducer. The biopsy is taken quickly. A number of biopsy "cores" are taken to be reviewed by a pathologist.

There are relatively no risks from this test. If you have a biopsy, you may feel limited discomfort.

It can take many days to get the biopsy results. If cancer is found, your urologist will talk about treatment options. If the biopsy shows no cancer, your urologist will talk with you about plans for follow-up.

Evaluation of Infertility

In some cases, transrectal ultrasound may be useful in finding abnormalities of the seminal vesicles and prostate. It can also be used to look at the testes.

Evaluation of the Female Urethra

Transvaginal ultrasound can be used to find a urethral diverticulum. A urethral diverticulum may cause urethral pain and frequent urinary tract infections.

Pediatric Urology

Ultrasound is ideal to use with children because it’s painless and done outside the body. Also, the results can be seen right away.

Ultrasound shows excellent images of the kidneys and bladder. It’s useful for checking birth defects of the urinary tract, problems with voiding, and to help treat urinary tract infections.

Evaluation of Blood Flow

A type of ultrasound called Doppler ultrasound can be used to see how blood flows in urological organs. This is useful in the testes and kidneys.