What Is an Ultrasound?

An ultrasound, which is also called sonography, is a test that uses sound waves to see inside your body. It creates real-time images or videos of internal organs and tissues without the need for incisions. The picture that an ultrasound generates is called a sonogram.

Ultrasounds can help doctors view, diagnose, and plan treatment for a variety of medical conditions. There are two main classifications of ultrasounds:

• Pregnancy ultrasound This type of ultrasound is used to create images of an unborn baby. It can confirm a pregnancy and provide doctors with information about a baby’s health, growth, and development.
• Diagnostic ultrasound A diagnostic ultrasound is used to help diagnose a health condition. Doctors can view various parts of the body, including the heart, liver, bladder, blood vessels, breasts, kidneys, thyroid, prostate, gallbladder, and female reproductive organs to look for signs of disease or other abnormalities.

Additionally, ultrasounds are sometimes used to help doctors perform medical procedures more precisely. For example, an ultrasound may be a useful tool for guiding needle placement during a biopsy (a procedure that involves removing a small sample of tissue to analyze in the lab). Certain types of ultrasounds can even be used therapeutically to treat specific conditions.

A doctor or specially trained technician usually performs an ultrasound.

You might need an ultrasound if you’re pregnant, so doctors can check on the health and development of your unborn baby.

A diagnostic ultrasound may be used to detect a variety of possible medical conditions. Your doctor might recommend this test if you’re having unusual symptoms in certain areas of the body. Diagnostic ultrasounds are commonly used to:

• Determine if blood is flowing normally
• Detect a structural problem in the heart
• Look for gallbladder blockages
• Check for abnormalities in the abdomen and kidneys
• Look for cancer or growths on the thyroid gland
• Examine a breast lump to see if it’s cancer
• Help determine the cause of pelvic pain, infertility, or abnormal menstrual bleeding in women
• Diagnose problems with the prostate gland in men
• Detect brain abnormalities in newborns
• Identify the source of pain, swelling, or infections

You may also need to have an ultrasound if you’re having a medical procedure, such as a biopsy.

Therapeutic ultrasounds are used to treat, rather than diagnose, certain medical conditions. For instance, therapeutic ultrasound is commonly used in physical therapy to heat muscles, tendons, and other tissues in the body. The deep heating is thought to decrease pain and speed up the healing process. People with chronic pain or injuries are often good candidates for this therapy.

Some types of therapeutic ultrasound techniques, such as high-intensity focused ultrasound (HIFU), are used to treat tumors, uterine fibroids, or tremors. HIFU doesn’t create images, but uses high-intensity and focused sound waves to alter or destroy tissues in your body.

Therapeutic ultrasound is also used for:

• Breaking up large kidney stones or gallstones
• Teeth cleaning
• Cataract removal
• Stimulating bone growth to heal fractures
• Surgical tissue cutting and hemostasis (stopping of blood flow)
• Guiding the delivery of drugs to specific tissues in the body

While ultrasound can be a useful tool, the test has its limitations. For example, ultrasound waves can’t create images of areas deep within the human body or those that are hidden by bone. Other imaging tests, such as computerized tomography (CT), magnetic resonance imaging (MRI), or X-rays, may be more suitable in these instances.

An ultrasound can be performed at a doctor’s office, hospital, or other type of medical facility. It usually takes about 30 to 60 minutes to perform the test.

During a standard, diagnostic ultrasound, you’ll lie down on a table, or be seated on a table, and expose the area that’s being examined. The technician first applies a gel to the skin to help prevent air pockets, which can block the sound waves that make the images.

Next, the provider will pass a device, called a transducer, over the area. The transducer sends sound waves into your body and collects the ones that bounce back, converting them into electrical signals. These signals are sent to a special computer that transforms them into images or videos you can view on a screen.

If you’re having a special type of ultrasound called Doppler ultrasound, the test will measure blood flow through arteries and veins in your body. With this ultrasound technique, the movement of blood cells causes a variation in the pitch of the reflected waves, which is known as the Doppler effect. A computer gathers and processes the sounds and creates images that show blood flow through the vessels.

While most ultrasounds are performed using a device outside your body, some may involve placing the device in your body. In this case, the transducer is attached to a probe that’s inserted into a natural orifice. Some examples of this type of ultrasound include:

• Transvaginal ultrasound The device is inserted into the vagina to examine the ovaries and uterus.
• Transrectal ultrasound A special transducer is placed in the rectum to obtain images of the prostate.
• Transesophageal echocardiogram With this test, a transducer is placed into the esophagus to get pictures of the heart. Patients are usually sedated for this procedure.

The way you prepare for an ultrasound will depend on the type of test you’re having. Some ultrasounds don’t require any preparations on your part.

If you’re having an ultrasound of the pelvis, your provider might tell you to drink water before the test. Ultrasounds that are done to examine the abdomen may require you to adjust your diet or fast beforehand.

It’s a good idea to wear loose, comfortable clothing to your appointment. Also, remove all jewelry from the area that will be examined.

Your doctor will let you know if you need to follow any special instructions before having your ultrasound.

There aren’t any known risks associated with ultrasound imaging. According to the U.S. Food and Drug Administration (FDA), ultrasounds have been used for more than 20 years and have an excellent safety track record.

Unlike other tests, such as CT scans and X-rays, ultrasounds don’t involve the use of radiation, which can cause harm.

However, the FDA also says that ultrasound energy has the capability of producing biological effects on the body, as the waves can heat tissue slightly. In some instances, ultrasound can also create small pockets of gas in body fluids or tissues. Additionally, the agency points out that the long-term effects of ultrasound are still not known. For these reasons, several organizations, including the American Institute of Ultrasound in Medicine, promote conservative use of ultrasound during pregnancy and discourage nonmedical ultrasounds made only for “keepsake” purposes.

A diagnostic ultrasound exam is usually painless. You may feel some minor discomfort if the transducer is inserted inside your body, but it shouldn’t hurt.

Depending on the type of ultrasound, the technician may ask you to hold your breath or remain very still for a few seconds. This allows them to obtain clearer images.

While ultrasound can be a useful tool, the test has its limitations. For example, ultrasound waves can’t create images of areas deep within the human body or those that are hidden by bone. Other imaging tests, such as computerized tomography (CT), magnetic resonance imaging (MRI), or X-rays, may be more suitable in these instances.

There are usually no complications or side effects associated with the use of ultrasound. However, experts recommend that ultrasounds be performed by medical professionals who have training in using the technology.

You should be able to resume your normal daily activities immediately after having a diagnostic ultrasound, unless your doctor tells you otherwise.

When your ultrasound is complete, a radiologist or other specially-trained doctor will interpret the results and send them to your doctor. Sometimes, the radiologist or doctor will discuss the findings with you right after your exam.

You may need to have a follow-up ultrasound or another type of imaging test. Be sure to keep all appointments with your provider.