An ultrasound test uses high-frequency sound waves to create images of internal organs or tissues. It works by sending low-energy sound waves against tissue. Some waves pass through and some are reflected (bounce back). As sound waves bounce back, they are recorded and displayed on a computer screen or television-type monitor.

The image created by an ultrasound is considered to be less clear than those obtained by using computed axial tomography (CAT scan) or magnetic resonance imaging (MRI). However, ultrasound is commonly used for a wide array of diagnostic studies since it is fast, generally noninvasive and relatively inexpensive. 

Ultrasound technology can help a physician diagnose and monitor the progress of various obstetric and gynecological conditions. These include:

• Pregnancy and pregnancy-related conditions
  

  

• Breast cancer and gynecological cancers, such as those of the ovaries, cervix, endometrium or vagina
  
  
• Measurement of follicular growth in fertility treatments
  
  
• Other conditions, such as dysfunctional uterine bleeding (DUB), uterine fibroids, polycystic ovarian syndrome (PCOS) and urinary system disorders

Ultrasound can also be used to help guide needles and other instruments under the skin and to the proper organ or body area.

Ultrasound, which is sometimes called ultrasonography or sonogram, uses high-frequency sound waves to create images of organs, blood vessels and tissues. The sound waves are too high for the human ear to hear, but they produce an image that allows physicians to view internal organs and to assess blood flow through various vessels. Ultrasound is often performed by a technician and then analyzed by a physician.

Inspired by sonar technology, which uses sound waves to detect objects underwater, ultrasound can help diagnose a wide range of diseases and conditions. It can be used alone or with other diagnostic procedures. Sonography is the medical term for the testing and recording of the ultrasound. Sound waves are sent by a transducer into the body. Some sound waves pass through tissue, and others bounce back. The returning sound waves are picked up by sensors connected to a computer, which measures the distance by using the elapsed time from transmission to reception.

Because ultrasound does not expose the patient to any radiation, it may be used as a substitute for x-ray imaging when diagnosing certain populations. These include pregnant women and infants, who may be more vulnerable to the negative effects of radiation.

Ultrasound can also help a physician detect, diagnose or monitor various obstetric and gynecological conditions. Because it uses low-energy sound waves, it is an invaluable tool to confirm and monitor a woman’s pregnancy. In the early stages of pregnancy, ultrasound, in combination with the date of the last menstrual period, can help reveal the fetus’ gestational age and due date. It also can:

• Reveal the gender of the fetus (not usually possible until the second trimester)
  
  
• Reveal the number of fetuses a woman is carrying
  
  
• Provide important details about growth rate and organ development in the fetus
  
  
• Record fetal heartbeat and breathing movements
  
  
• Provide important insights about the fetus’ overall health and reveal signs of potential health problems, such as possible birth defects
  
  
• Provide information about the location of the placenta (organ that connects the fetus to the uterus to provide oxygen and nutrients and to remove waste products)

Women who have an ultrasound early in pregnancy should not expect to view a recognizable form of a baby in the image that is produced. In the first ultrasound of the pregnancy (often performed at six to seven weeks), the most obvious image is usually that of the fetus’ pumping heart. A physician or other healthcare professional trained in analysis will interpret the image.

In addition to pregnancy, ultrasound can provide vital information on diseases, including the following:

• Dysfunctional uterine bleeding (DUB). Occurs when the menstrual period is not regular, when bleeding lasts longer than normal, is heavier than normal, or when bleeding patterns change.
  
  
• Polycystic ovarian syndrome (PCOS). Hormone imbalance that can cause irregular periods, unwanted hair growth and acne. Ultrasound imaging of the uterus is helpful in diagnosing this disorder.
  
  
• Uterine fibroids. Noncancerous tumors that grow slowly and usually require no treatment. Ultrasound can be used to help confirm the presence of fibroids initially detected during a pelvic examination.
  
  
• Cancer and other disorders. The test is especially effective when a tumor is located in soft tissue and it is unclear whether an abnormality is a cyst (sac of fluid) or a solid mass. Cancers that can be detected with ultrasound include those of the ovaries, endometrium, cervix, vagina and breast. However, further testing (e.g., biopsy) is necessary to confirm diagnosis of cancer.

• Urinary system disorders. These are disorders – including infections – of the kidneys, ureters, bladder or urethra.

Ultrasound can also be used to examine the internal structures of the abdomen (liver, spleen, pancreas, etc.), as well as detect gallstones and kidney stones. Other common uses for ultrasound include the detection of fluid, cysts, tumors or abscesses in the abdomen or liver, reduced blood flow due to clots or arteriosclerosis in the legs, aneurysms of the aorta and the structure of the thyroid gland in the neck.

Ultrasound may be used for therapeutic reasons in physical and occupational therapy. The thermal effects have been found to be helpful for treatment of musculoskeletal injuries, breaking down scar tissue and helping to stretch tendons.

Finally, ultrasound can be used to guide needle biopsies and other procedures. In some cases, ultrasound is used to help a physician guide a needle or other instrument to a location under the skin surface. For example, a physician may use the image from an ultrasound to help guide a needle to the site of a tumor to extract cells from a tumor for analysis in a laboratory. Additionally, ultrasound is used to guide a needle into the uterine cavity during an amniocentesis.

There are various techniques of ultrasound imaging, including:

• A-mode, or amplitude modulation, which is recorded as a single line showing the time needed to reach the organ and return to the transducer, a small device that sends ultrasound waves through the body.
  
  
• B-mode, which is brightness modulation
  
  
• Gray scale, which shows the texture of various organs in shades of white and gray
  
  
• Real-time imaging, which shows rapid multiple views of tissues in motion
  
  
• Doppler imaging, which shows increased blood vessels within a mass of tissue
  
  
• Echocardiogram, which shows heart anatomy and function

Some of the most common obstetric and gynecological ultrasound tests include:

• Abdominal ultrasound. Used to view the kidneys, pancreas, gallbladder, pelvis and other internal organs in the abdomen area. A technique used in fertility assessment involves filling the uterus with a saline solution before performing an ultrasound (sonohysterography) in order to view the uterine cavity and fallopian tubes.
  
  
• Pregnancy ultrasound. Used to check the development of the fetus, including the baby’s heartbeat, size, location and, sometimes gender. If congenital heart defects are suspected in a fetus, a fetal echocardiogram may be performed.
  
  
• Transvaginal ultrasound. Uses a higher frequency of sound than an abdominal ultrasound, which enhances the detail but limits the area that can be viewed. It is used to view the ovaries and uterus and to confirm a pregnancy early in the first trimester. It can also determine an ectopic pregnancy  or molar pregnancy or the viability of a pregnancy when a woman is experiencing bleeding. Transvaginal ultrasounds involve placing an imaging tool similar to a wand in the vagina to view the internal organs and tissues.
  
  
• Breast ultrasound. Used to provide a closer look at a possible breast mass. It can be performed in addition to a mammogram to help determine if a mass is fluid or solid. Breast ultrasound can also be used to determine if a breast implant has ruptured.
  
  
• Interventional ultrasound. Used to a guide a surgeon during a minimally invasive procedure, such as in the placement of needles during a breast biopsy or the drainage of infections.
  
  
• Renal ultrasound. Used to view the kidneys and the rest of the urinary tract.
  

  

Preparations for an ultrasound test depend greatly on the type of ultrasound being performed but most ultrasound tests require little or no preparation. For ultrasounds being performed on internal organs, such as the gallbladder, patients may be asked to avoid eating or drinking for six to eight hours before the examination.

For other ultrasounds, such as pregnancy or bladder tests, the patient may be asked to drink up to six glasses of water one hour prior to the test to fill the area with extra fluid. The excess fluid in the bladder helps to move air-filled bowel loops away from the area of concern for a clearer view.

In preparation for an ultrasound, it may be helpful to ask a healthcare provider about:

• Eating or drinking restrictions prior to the test
• Taking any medications prior to the test
• Smoking or using nicotine products before the test
• Avoiding soda or other carbonated drinks before the test
• Wearing loose-fitting, comfortable clothing
• Leaving jewelry and valuables at home
• Length of time to conduct the test

Most often, ultrasounds are performed on an outpatient basis, but these tests may be used in hospitals as part of diagnostic patient care. In general, most ultrasounds follow a similar procedure:

1. Depending on the area being tested, the patient may lie on a padded examining table during the test. During the actual test, which normally takes only about 20 to 30 minutes, it may be necessary to change into a hospital gown depending on the area to be examined.
   
   
2. A small amount of water-soluble gel, which acts as a conducer, is placed on the part of the body to be tested and/or directly on the transducer, a small device that sends ultrasound waves through the body. The gel does not harm the skin or stain clothing. It is important to note that the ultrasound’s transducer should not be placed over an open or draining wound.
   
   
3. The technician places the transducer on the part of the body to be scanned. In some tests, a probe transducer may be placed within an opening, such as the vagina or anus.
   
   
4. The sound waves sent from the transducer bounce off the structures within the body and the information is deciphered by the computer to create the ultrasound images.
   
   
5. The ultrasound images then appear on the television monitor and the moving pictures can be recorded as still images that can be printed or saved on videotape.

There is little or no pain associated with the ultrasound test though there may be some discomfort with internal ultrasounds, such as a transvaginal procedure. During the examination, a physician may be present with the technician to interpret the results. If the physician is not present, the results may be shown to the physician prior to completion of the test. This allows the physician to request additional views or images if necessary.

Once the test is completed, the images are evaluated by a radiologist and the results are sent to the patient’s physicians. It is important the patient indicate all of the physicians or facilities that should receive a copy of the ultrasound report. If the ultrasound shows a problem or an area of concern, additional diagnostic tests (e.g., mammography, CAT scan) are usually recommended.

In extensive studies, no risks associated with ultrasound have been documented. Ultrasounds are considered to be extremely safe, with no harmful side effects associated with this procedure. Unlike x-rays, there is no exposure to radiation during an ultrasound. This test is a noninvasive procedure that is widely available, easy to use and is considered painless.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about ultrasound:

Regular ultrasound

1. What type of ultrasound will I undergo?
   
   
2. Why is ultrasound being used rather that an alternative imaging procedure?
   
   
3. Should I follow any special preparations or restrictions prior to my ultrasound?
   
   
4. What type of conditions can be detected with this ultrasound?
   
   
5. What type of additional testing might be necessary?
   
   
6. When can I expect to receive the results of my ultrasound and by whom?

Pregnancy ultrasound

1. When will I have my first pregnancy-related ultrasound?
   
   
2. Can the ultrasound be done in my ObGyn’s office?
   
   
3. What information will be revealed about my baby?
   
   
4. What types of medical conditions can be detected with my ultrasounds?
   
   
5. How often can I expect to have ultrasounds throughout my pregnancy?
   
   
6. Can an ultrasound indicate the need for additional tests or treatment?