Many people who hear the term "ultrasound" likely picture a pregnant woman in their doctor's office getting a sneak peek of the baby growing inside her womb — perhaps even a gender reveal. But while fetal imaging is one of the most common uses of ultrasounds, this diagnostic tool actually has many applications.
What Is an Ultrasound?
Ultrasound is a diagnostic medical tool that uses sound waves to produce images of the inside of your body. It also can be used to treat certain conditions. Also called sonography, ultrasound images are usually taken from outside your body, but some are taken with devices inserted inside the body.
Ultrasound vs. X-ray
Ultrasound and X-ray are both imaging tests. X-rays create pictures of the inside of your body using a small amount of radiation. Most of us are familiar with X-ray imaging of our bones or teeth, but X-ray images can diagnose a range of conditions and injuries. They are used to examine bones and soft tissue. An ultrasound uses high-frequency sound waves to create these images.
Ultrasound vs. sonogram
Ultrasound is the test used for imaging. Sonogram is the image an ultrasound produces.
How Does an Ultrasound Work?
Ultrasound waves are produced by an instrument called a transducer, which sends high-frequency sound waves, inaudible to human ears, into the body and then records the echoes as the sound waves bounce back to determine the size, shape, and consistency of soft tissues and organs.
This information is relayed in real time to produce images on a computer screen. Ultrasound technicians, or sonographers, have special training in how to perform the test. Then a radiologist or your doctor will interpret the ultrasound images. This technology can help diagnose and treat certain conditions.
Ultrasound Uses
Ultrasound imaging has many uses in medicine, from confirming and dating a pregnancy to diagnosing certain conditions and guiding doctors through precise medical procedures.
Pregnancy. Ultrasound images have many uses during pregnancy. Early on, they may be used to determine due dates, reveal the presence of twins or other multiples, and rule out ectopic pregnancies. They also are valuable screening tools that help detect potential problems, including some birth defects, placental issues, breech positioning, and others. Many expectant parents look forward to learning the sex of their babies via an ultrasound midway through a pregnancy. And later in pregnancy, doctors can even use ultrasounds to estimate how large a baby is just before delivery.
Diagnostics. Doctors use ultrasound imaging in diagnosing a wide variety of conditions affecting the organs and soft tissues of the body, including the heart and blood vessels, liver, gallbladder, spleen, pancreas, kidneys, bladder, uterus, ovaries, eyes, thyroid, and testicles. Ultrasounds do have some diagnostic limitations, however; sound waves do not transmit well through dense bone or parts of the body that may hold air or gas, such as the bowel.
Use during medical procedures. Ultrasound imaging can help doctors during procedures such as needle biopsies, which require the doctor to remove tissue from a very precise area inside the body for testing in a lab.
Therapeutic applications. Ultrasounds sometimes are used to detect and treat soft tissue injuries.
Types of Ultrasounds
Most ultrasounds are done using a transducer on the surface of the skin. Sometimes, however, doctors and technicians can get a better diagnostic image by inserting a special transducer into one of the body's natural openings.
There are three types of ultrasounds:
Pregnancy ultrasound
Doctors use a pregnancy ultrasound to:
- Confirm your pregnancy
- Determine how many fetuses you're carrying
- Check the level of amniotic fluid
- Estimate the length of your pregnancy and the age of your fetus
- Check the fetus's position, growth, heart rate, and movement
- Check for problems in the fetus's heart, brain, or spinal cord
- Determine the fetus's biological sex
Anatomy ultrasound
An anatomy ultrasound is recommended around your 20th week of pregnancy to look at fetal development and growth. During the 20-week ultrasound, the medical technician does a thorough exam of your fetus's anatomy — counting and inspecting limbs; measuring head and bone size; and looking at facial features, internal organs, and structures such as the brain, heart, kidneys, bladder, and spine.
Diagnostic ultrasound
These ultrasound tests image various internal tissues and organs to learn more about symptoms you may be having or why a blood test may be abnormal. Sometimes during a diagnostic ultrasound, an ultrasound probe is inserted into your body. These imaging tests include:
- Transvaginal ultrasound, in which a transducer wand is placed in the vagina to get better images of your uterus and ovaries.
- Transrectal ultrasound, which is sometimes used in the diagnosis of prostate conditions.
- Transesophageal echocardiogram, which probes the esophagus so that the sonographer can obtain clearer images of the heart.
A diagnostic ultrasound may also be used to examine your:
- Abdomen
- Kidneys
- Breasts
- Pelvis
- Thyroid gland
Functional ultrasound
This type of an ultrasound looks at small changes in the brain's blood volume and flow to determine brain and central nervous system activity. A new technology, functional ultrasound has shown promising results for use in brain surgery for adults and brain mapping in preterm babies.
Guidance ultrasound for surgery or procedures
These ultrasounds offer doctors guidance as to the precise location inside your body a sample of fluid or tissue should be taken from. An ultrasound can also assist in procedures such as in vitro fertilization, intrauterine device placement, and nerve blocks.
Therapeutic ultrasound
A low-frequency ultrasound has been used to treat various conditions since the 1950s. Among the FDA-approved uses of a therapeutic ultrasound are:
- Cancer
- Uterine fibroids
- Glaucoma
- Kidney stones
- Plantar fasciitis
- Liposuction
- Bone fractures
There can be some significant side effects of using an ultrasound for treatment, so your health care professional will carefully weigh the benefits and drawbacks before using this manner of treatment.
Other uses of an ultrasound
Additionally, ultrasound technology has advanced to allow for other types of imaging:
- Doppler is a special type of ultrasound that creates images of blood flow through vessels.
- Bone sonography helps doctors diagnose osteoporosis.
- Echocardiograms are used to view the heart.
- Three-dimensional imaging adds another dimension to the ultrasound image, creating three-dimensional interpretations rather than the flat two-dimensional images that are made with the traditional ultrasound.
- Four-dimensional ultrasounds show three-dimensional images in motion.
Benefits of an Ultrasound
Ultrasounds offer many advantages:
- They are generally painless and do not require needles, injections, or incisions.
- Patients aren't exposed to ionizing radiation, making the procedure safer than diagnostic techniques such as X-rays and CT scans. In fact, there are no known harmful effects when used as directed by your health care professional.
- Ultrasounds capture images of soft tissues that don't show up well on X-rays.
- Ultrasounds are widely accessible and less expensive than other methods.
Is an Ultrasound Safe?
Studies show that ultrasounds are generally safe. There are no known harmful side effects, and there is virtually no discomfort during the test. In addition, ultrasounds do not use radiation, as X-ray tests do. The possible long-term effects of these are not known.
What to Expect During an Ultrasound
Depending on the type of ultrasound you are having, your doctor may offer special instructions, such as not eating or drinking anything for a number of hours before the test. Or you may be advised to drink several glasses of water in the time leading up to the test and refrain from using the bathroom to ensure that your bladder is full.
You should wear comfortable clothing that is easy to remove or partially remove. In some cases, you may need to disrobe or wear a gown, but often an ultrasound technician can easily access the area of the body that is being screened without your having to take off your clothes.
The technician will apply a water-based gel to the area. This is so that the transducer can easily glide across your skin without any air in between. They may be looking for specific markers and may make measurements or notes while the test is in progress.
After an Ultrasound
A typical ultrasound takes between 30 minutes and 1 hour. Ultrasounds usually are not uncomfortable, and you are awake and alert during the procedure. Often a technician will discuss what they are seeing during the test, but in some instances, you may need to wait to discuss the findings with your doctor.
Most often, you'll be able to go home after your ultrasound. If you aren't sedated, you should be able to drive yourself home and eat and drink normally. With an endoscopic ultrasound requiring sedation, you will probably have to wait a couple of hours after the procedure for the anesthesia to wear off, and someone will need to pick you up.
Getting your results
Getting your results depends on the type of ultrasound you have. During pregnancy, you may get results right then. For other types of scans, a radiologist or other specialist may need to examine and interpret the images and send the results to your doctor.
How Much Does an Ultrasound Cost?
The cost of your ultrasound depends on where you live and the type of scan you get. Generally, a pregnancy ultrasound can cost as little as $200 up to $1,000 or more. Most insurance companies cover the cost of prenatal ultrasounds, and you should check with your insurer for out-of-pocket costs for other types of ultrasounds.
Takeaways
An ultrasound is a test that takes images inside your body. The test uses high-frequency sound waves to create pictures in real time of organs and soft tissue. Not just a tool during pregnancy, an ultrasound can be used to examine your kidneys, breasts, vascular system, thyroid gland, and pelvic organs.
Ultrasound FAQs
What is done during an ultrasound?
During an ultrasound, a technician uses an external device called a transducer to scan and take pictures of structures inside your body. An ultrasound can also be conducted through a probe that's inserted into a body opening. Before the procedure, gel is placed on your skin to help transmit the high-frequency ultrasound waves to and from the transducer.
Why should my bladder be full before an ultrasound?
You need a full bladder for an abdominal ultrasound. For other types ultrasound procedures, a full bladder isn't necessary. Typically, you'll be asked to drink several glasses of water or liquid one or more hours before your ultrasound but not empty your bladder until the test is completed.
What is seen in a 20-week ultrasound?
Also called an anatomy ultrasound, this scan in the 20th week of pregnancy is a thorough examination of a fetus's development and growth.
Is an ultrasound only for pregnancy?
No. Ultrasounds are also used to diagnose and treat certain conditions and help doctors precisely locate parts of your body during some procedures.
Can I eat before an ultrasound?
It depends on the type of ultrasound you're having. If your abdominal cavity is being scanned, you may be asked to not eat or drink for several hours before your exam. For a pelvic ultrasound, you may be asked to fill up your bladder with water before your test. Your doctor will let you know how to prepare for your type of ultrasound.