Ultrasound is a noninvasive imaging test that shows structures inside your body using high-intensity sound waves. Healthcare providers use ultrasound exams for several purposes, including during pregnancy, for diagnosing conditions and for image guidance during certain procedures.
Ultrasound (also called sonography or ultrasonography) is a noninvasive imaging test. An ultrasound picture is called a sonogram. Ultrasound uses high-frequency sound waves to create real-time pictures or video of internal organs or other soft tissues, such as blood vessels.
Ultrasound enables healthcare providers to “see” details of soft tissues inside your body without making any incisions (cuts). And unlike X-rays, ultrasound doesn’t use radiation.
Although most people associate ultrasound with pregnancy, healthcare providers use ultrasound for many different situations and to look at several different parts of the inside of your body.
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During an ultrasound, a healthcare provider passes a device called a transducer or probe over an area of your body or inside a body opening. The provider applies a thin layer of gel to your skin so that the ultrasound waves are transmitted from the transducer through the gel and into your body.
The probe converts electrical current into high-frequency sound waves and sends the waves into your body’s tissue. You can’t hear the sound waves.
Sound waves bounce off structures inside your body and back to the probe, which converts the waves into electrical signals. A computer then converts the pattern of electrical signals into real-time images or videos, which are displayed on a computer screen nearby.
There are three main categories of ultrasound imaging, including:
Healthcare providers often use ultrasound (often called prenatal or obstetric ultrasound) to monitor you and the fetus during pregnancy.
Providers use prenatal ultrasound to:
Most healthcare providers recommend an ultrasound at 20 weeks pregnant. This test tracks the fetus’s growth and development during pregnancy. This ultrasound may also show the biological sex of the fetus. Tell your technician if you do or do not want to know the sex.
Your provider may order extra scans to get answers to any questions or concerns, such as the potential for congenital conditions.
Providers use diagnostic ultrasounds to view internal parts of your body to see if something is wrong or not working properly. They can help your provider learn more about what’s causing a wide range of symptoms, such as unexplained pain, masses (lumps) or what may be causing an abnormal blood test.
For most diagnostic ultrasound exams, the technician places the transducer (probe) on your skin. In some cases, they may need to place the probe inside your body, such as in your vagina or rectum.
The type of diagnostic ultrasound you have depends on the details of your case.
Examples of diagnostic ultrasounds include:
Providers sometimes use ultrasound to perform certain procedures precisely. A common use of ultrasound is to guide needle placement to sample fluid or tissue from:
Examples of other procedures that may require ultrasound guidance include:
For ultrasounds during pregnancy, the traditional ultrasound is a two-dimensional (2D) image of the fetus. 2D ultrasound produces outlines and flat-looking images, which allows your healthcare provider to see the fetus's internal organs and structures.
Three-dimensional (3D) ultrasound allows the visualization of some facial features of the fetus and possibly other body parts such as fingers and toes. Four-dimensional (4D) ultrasound is 3D ultrasound in motion. Providers rarely use 3D or 4D fetal ultrasound imaging for medical purposes, though it can be useful in diagnosing a facial or skeletal issue. They do, however, use 3D ultrasound for other medical purposes, such as evaluating uterine polyps and fibroids.
While ultrasound is generally considered to be safe with very low risks, the risks may increase with unnecessary prolonged exposure to ultrasound energy or when untrained users operate an ultrasound machine. Because of this, the U.S. Food and Drug Administration (FDA) advises against getting a 3D ultrasound for non-medical reasons such as for “keepsake” moments or entertainment.
A doctor or a healthcare provider called an ultrasound technician or sonographer performs ultrasounds. They’re specially trained to operate an ultrasound machine properly and safely.
It’s important to always have your ultrasound performed by a medical professional and in a medical facility.
The preparations will depend on the type of ultrasound you’re having. Some types of ultrasounds require no preparation at all.
For ultrasounds of the pelvis, including ultrasounds during pregnancy, of the female reproductive system and of the urinary system, you may need to fill up your bladder by drinking water before the test.
For ultrasounds of the abdomen, you may need to adjust your diet or fast (not eat or drink anything except water) for several hours before your test.
In any case, your healthcare provider will let you know if you need to do anything special to prepare for your ultrasound. They may give you instructions during an appointment or when scheduling your ultrasound. Instructions may also be available in your electronic medical records if you use such a system.
Preparation for an ultrasound varies depending on what body part you’ll have scanned. Your provider may ask you to remove certain pieces of clothes or change into a hospital gown.
Ultrasounds that involve applying the transducer (probe) over your skin (not in your body), follow these general steps:
An ultrasound test usually takes 30 minutes to an hour. If you have any questions about your specific type of ultrasound, ask your healthcare provider.
Ultrasounds that are performed externally (over your skin) are generally not painful. You won’t feel the sound waves that ultrasound uses. If you have to have a full bladder for the procedure, it may be uncomfortable. It may also be uncomfortable to lay on the exam table if you’re pregnant.
Ultrasounds that go inside body cavities, such as your vagina or rectum, may be uncomfortable, but they shouldn’t hurt.
Yes, research to date has largely shown ultrasound technology to be safe with no harmful side effects. Ultrasound doesn’t use radiation, unlike some other medical imaging tests, such as X-rays and CT scans.
Still, all ultrasounds should be done by a professional who has training in using this specialized technology safely.
The time it takes to get your results depends on the type of ultrasound you get. In some cases, such as prenatal ultrasound, your provider may analyze the images and provide results during the test.
In other cases, a radiologist, a healthcare provider trained to supervise and interpret radiology exams, will analyze the images and then send the report to the provider who requested the exam. Your provider will then share the results with you or they may be available in your electronic medical record (if you have an account set up) before your provider reviews the results.
Ultrasound can help providers diagnose a wide range of medical issues, including:
If you need an ultrasound, you may want to ask your provider the following questions:
A note from Cleveland Clinic
Ultrasounds are common, safe and effective imaging tests. Make sure you get an ultrasound from a well-trained professional (sonographer) who understands how to use this technology properly. If you have any questions about your specific ultrasound test, talk to your healthcare provider. They’re available to help.
Last reviewed by a Cleveland Clinic medical professional on 04/12/2022.
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