Version July 2025
Please read the Disclaimer at the end of this page.
What is an ultrasound? —
This is a type of imaging test. It uses sound waves to create pictures of the inside of the body (figure 1). Doctors use it to see the organs and structures in the body. The images appear on a screen during the test.
Ultrasound can show things like:
●The size of an organ or other structure
●How an organ is working
●Blood flow
●If there is injury or disease
●If there is a collection of fluid, such as an abscess
What are the different types of ultrasounds? —
Different types of ultrasounds are used in different situations. You might have to go to a special department for an ultrasound. Or if you are in the hospital or the emergency department, the machine might be brought to your bedside.
Examples of ultrasounds include:
●Diagnostic ultrasound – This is used to help the doctor learn more about a condition.
●Procedural ultrasound – This is used to guide the doctor during a procedure like a biopsy, an injection, or placing a drain.
●Point-of-care ultrasound – This is typically done in the emergency department when the machine is brought to the bedside. It is often used when a person has a serious injury. It gives the doctors a quick view of the chest and belly to see if there is damage to an organ. It can also be used to help the doctor during procedures, such as placing a catheter or draining an abscess.
●3D and 4D ultrasounds – Just like regular ultrasounds, 3D and 4D ultrasounds use sound waves to create pictures. With a 3D ultrasound, the images are stacked together to create a 3-dimensional image. A 4D ultrasound stacks the pictures together to create a moving image, like a video. These are often done during pregnancy to create images of the developing baby.
How do I prepare for an ultrasound? —
The doctor or nurse will tell you if you need to do anything special to prepare. This depends on why you are having an ultrasound and which parts they need to see.
You might be asked to:
●Not eat anything for a period of time before the ultrasound
●Eat or drink a certain kind of food or amount of liquid before the ultrasound
●Avoid using the bathroom until after the ultrasound
In many cases, you do not need to do anything special before.
What happens during an ultrasound? —
When it is time for the procedure:
●You might need to remove your clothes and put on a gown. You might be asked to lie down.
●The person doing the ultrasound will put a small amount of gel on your skin or on a special wand called a "transducer" or "probe."
●For most ultrasounds, they will gently press the transducer against your skin and move it around to create images. In some cases, the ultrasound probe is inserted into an opening in the body, like the throat, vagina, or rectum.
●Images will appear on a computer screen. This lets the doctor see the organs and structures in that area of your body. In some cases, color images show where and how fast blood is flowing.
●It does not usually hurt. But you might feel pressure when the transducer presses against your skin. You might need to change positions or hold your breath for a few seconds.
●An ultrasound usually takes less than an hour.
What happens after an ultrasound? —
The person doing the ultrasound will wipe the gel off your skin, and you will get dressed.
The doctor will review the ultrasound. The results might help them learn more about any problems you are having. You might need to have other tests or procedures after. Discuss all test results with your doctor. They can help you understand what the results mean.
What are the risks of an ultrasound? —
Your doctor will talk to you about all the possible risks, and answer your questions. An ultrasound does not usually have any risks to your health. It does not expose you to radiation like an X-ray.
Patient education: Abdominal ultrasound (The Basics)
Patient education: Breast ultrasound (The Basics)
Patient education: Carotid ultrasound (The Basics)
Patient education: Duplex ultrasound (The Basics)
Patient education: Endobronchial ultrasound (The Basics)
Patient education: Endoscopic ultrasound (The Basics)
Patient education: Pelvic ultrasound (The Basics)
Patient education: Prenatal ultrasound (The Basics)
