What is an ultrasound?
Ultrasound (also called sonography or ultrasonography) is a noninvasive diagnostic imaging test. It uses high-frequency sound waves to create real-time pictures or video of internal organs or other tissues, such as blood vessels. An ultrasound picture is called a sonogram.
Ultrasound enables healthcare providers to “see” details of soft tissues inside the body without making any incisions.
How does ultrasound work?
Ultrasound works similarly to sonar technology, which uses sound waves to detect objects beneath the ocean’s surface. Healthcare professionals called diagnostic medical sonographers are trained to use an ultrasound probe. The probe is a device that emits sound waves.
A sonographer puts a special gel on the body part they will examine. They pass the probe over or inside that area. Sound waves from the probe bounce off internal tissues. The sound waves create a live picture and display it on a computer screen nearby. You can’t hear the sound waves.
Why do healthcare providers perform ultrasound tests?
Healthcare providers commonly use ultrasound to check an unborn baby’s health and development during pregnancy. Ultrasound can also help your provider learn more about what’s causing a wide range of symptoms (such as unexplained pain, lump or inflammation).
Your provider may recommend an ultrasound to evaluate the:
- Digestive system (such as the liver, pancreas or gallbladder).
- Urinary system (such as the kidneys or bladder).
- Heart and blood vessels.
- Female reproductive system (such as the ovaries or uterus).
- Brain, hips or spine (in babies).
Healthcare providers sometimes use ultrasound to perform certain procedures precisely. For example, ultrasound can guide needle placement in a needle biopsy.
How should I prepare for an ultrasound?
Certain factors (like having a full bladder or stomach) can make ultrasound pictures turn out more or less detailed. Your healthcare provider will give you instructions before your test to help ensure clear images.
You may not need to do anything to prepare. Or your provider may ask you to:
- Avoid using the bathroom before your scan.
- Drink a specific amount of water right before your scan.
- Stop eating or drinking a certain number of hours before having an ultrasound.
How is an ultrasound performed?
Preparation 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. For the scan, you will lie on your side or back on a comfortable table. An ultrasound test usually takes 30 minutes to an hour.
During the test, a trained professional:
- Applies gel: You’ll have a small amount of water-soluble gel on your skin over the area to be examined. This gel does not harm your skin or stain your clothes.
- Uses the scanner: The technician moves a handheld instrument over the gel. The scanner may move on your skin or inside your body.
- Asks you to hold still: The provider may tell you to hold your breath for a few seconds. Being very still can help create clearer pictures.
- Cleans your skin: The technician wipes off any remaining gel on your skin.
When is an ultrasound done during pregnancy?
Healthcare providers often use obstetric ultrasound (also called prenatal ultrasound) to monitor a mother and baby during pregnancy. Your provider may use abdominal or transvaginal ultrasound early in pregnancy to determine:
- Your due date.
- Your baby’s well-being, including heart rate.
- How far along you are in your pregnancy (called your baby’s gestational age).
- Presence of multiples (more than one baby).
- Most doctors recommend an ultrasound at 20 weeks’ gestation. This test tracks your unborn baby’s growth and development during pregnancy. This ultrasound may also show your baby’s biological sex. Tell your technician if you do or do not want to know the sex.
Additional ultrasounds (earlier or later in pregnancy) can offer a detailed view of the uterus or ovaries. Your provider may order extra scans to get answers to any questions or concerns, such as the potential of birth defects (congenital abnormalities).
What is 3D vs. 4D ultrasound?
Most ultrasounds create flat (or two-dimensional) images. Some maternal and fetal medicine providers offer 3D or 4D ultrasounds. Both 3D and 4D ultrasound provide a more lifelike-appearing view of your baby inside the womb. 4D ultrasound provides live motion. It shows the real-time movement of your baby (like watching a movie).
What are other types of ultrasound?
Doppler ultrasound uses sound waves to capture blood flow inside blood vessels. Regular ultrasound does not offer this detail.
The type of ultrasound you have depends on the details of your case. It often depends on the area your provider is assessing:
- Abdominal ultrasound: An ultrasound probe (also called a transducer) moves across the skin of your midsection (belly) area.
- Endoscopic ultrasound: A provider carefully guides a flexible tube (called an endoscope) down your throat. This tube has an ultrasound probe at the end. The probe shows the inside and outside of digestive or abdominal organs, such as the liver. During this procedure, your provider may also remove a small tissue sample for further analysis in a laboratory.
- Transesophageal echocardiogram: During this specialized procedure, a provider carefully guides an endoscopic probe down your throat. The probe takes pictures of the heart and nearby blood vessels.
- Transrectal ultrasound: Your provider inserts an ultrasound probe transducer into the rectum. It evaluates the rectum or other nearby tissues, such as the prostate (in men).
- Transvaginal ultrasound: Your technician inserts a probe inserted into the vagina. It shows reproductive tissues such as the uterus or ovaries. A transvaginal ultrasound is sometimes called a pelvic ultrasound because it evaluates structures inside the pelvis (hip bones).
- Contrast-enhanced ultrasound. In this procedure, your provider injects contrast agents through a catheter or IV during your ultrasound. These agents help give a clearer image of your organs (typically used for kidney, liver and bladder).
What should I expect after an ultrasound?
After the test, the technologist usually sends the images to a radiologist (doctor who specializes in reading medical images) for review. In some cases, a provider may review the images on the computer screen during your test.
After radiologists review your ultrasound pictures, they send a written report to your provider. Your provider discusses the test results with you. You usually get results within days of your test.
Are ultrasound scans safe?
Yes, research to date has largely shown ultrasound technology to be safe, with no harmful side effects. Ultrasound does not 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. It is safer to have the scan only at your healthcare provider’s office, not at a retail location such as a baby store.
Recovery and Outlook
Are ultrasound results immediate?
If your provider sits with you during the ultrasound test, you may know your results right away. Otherwise, you’ll probably get results within about a week.
What can ultrasound detect?
Ultrasound can help providers diagnose a wide range of medical issues, including:
- Abnormal growth (tumor), such as cancer, ovarian cysts or thyroid nodules.
- Blood clots.
- Enlarged spleen.
- Ectopic pregnancy (when a fertilized egg implants outside of the uterus).
- Heart problems, such as coronary artery disease or congenital heart conditions.
- Kidney or bladder stones.
- Cholecystitis (gallbladder inflammation).
- Varicocele (enlarged veins in the testicles).
What should I ask my healthcare provider?
If you need an ultrasound test, you may want to ask your provider:
- What type of ultrasound do I need?
- Do I need any other tests?
- What should I do to prepare for my ultrasound?
- When should I expect to get test results?
A note from Cleveland Clinic
Most experts view ultrasound as a safe, accurate imaging test. It usually causes little to no discomfort. Providers use ultrasound to diagnose or give information about a wide range of medical issues. It can spot routine concerns and more serious problems. Make sure you get an ultrasound from a well-trained professional (sonographer) who understands how to use this technology safely.
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