Sonography: How a Sonogram Test Works and What It Shows

Sonography is a diagnostic medical test that uses high-frequency sound waves, or ultrasound waves, to create images of tissues, glands, organs, and blood or fluid flow within the body. This test is also referred to as an ultrasound or sonogram.

Sonography uses a device called a transducer on the surface of the skin to send ultrasound waves and listen for an echo. A computer translates the ultrasound waves into an image. A trained technician can see, measure, and identify structures in the image. A healthcare provider then reads the images to help diagnose the issue or problem at hand.

This article explains the purpose and limitations of sonography. To demystify the test, this article also explains what to expect before and during the test.

Purpose of the Test

A sonogram captures a live image of what's going on inside the body. It functions like a camera that takes pictures of body parts or processes in real time.

Sonography is useful for evaluating the size, shape, and density of tissues to help diagnose certain medical conditions. Traditionally, ultrasound imaging is great for looking into the abdomen without having to cut it open.

 Abdominal ultrasound is often used to diagnose:

• Gallbladder disease or gallstones
• Kidney stones or kidney disease
• Liver disease
• Appendicitis
• Ovarian cysts
• Ectopic pregnancy
• Uterine growths or fibroids and other conditions

A sonogram is most commonly used to monitor the development of the uterus and fetus during pregnancy. It can also be used to evaluate glands, breast lumps, joint conditions, bone disease, testicular lumps, or to guide needles during biopsies.

Sonography can also recognize blood or fluid flow that moves toward or away from the transducer. It uses color overlays on the image to show the direction of the flow. Very hard and dense tissues or empty spaces, such as organs filled with gas, do not conduct ultrasound waves and therefore cannot be viewed on a sonogram.

Physicians often order a sonogram before moving on to imaging technologies that have more potential for complications. Computerized tomography (CT), for example, exposes you to significant levels of radiation.

Magnetic resonance imaging (MRI) uses an extremely strong magnet to capture an image. The strength of an MRI magnet can limit its use in patients with metal or devices in their bodies, such as some pacemakers.

Precautions and Risks

A sonogram is a noninvasive imaging test that has no known complications. Ultrasound waves are thought to be harmless.

While the energy of the ultrasound waves could potentially irritate or disrupt tissues with prolonged exposure, the computer modulates the power of the sound. Also, a trained technician uses techniques to minimize exposure times and angles, making sonography the safest of all imaging tests.

Before the Test

Healthcare providers order sonography as a first-line test, usually together with blood tests. Make sure you ask your provider if you should follow any special instructions before your sonogram.

In an emergency setting, sonography will typically be performed right away. For a test on a future date, find out if you should or should not eat or drink anything before the test. The answer may change depending on the purpose of the test.

For example, healthcare providers often ask patients to fast (not eat or drink) for six hours before an abdominal ultrasound to look at the gallbladder. But they may tell you to drink several glasses of water and not urinate before a sonogram of the bladder.

Timing

A sonogram usually doesn’t take longer than 30 minutes. In most cases, it’s important to arrive about 15 minutes before the test to fill out forms and possibly answer other questions. If the test requires that you drink fluids to fill your bladder, you might need to drink water before the test.

Once the technician acquires all the pictures, they will check with the radiologist (a healthcare provider trained to read images) to make sure no other views are required. Medical protocols call for the radiologist to interpret the images from a sonogram before sending a report to the healthcare provider. The provider then shares the results with the patient.

Location

Sonography is done at most imaging centers, hospitals, and some obstetrics offices. The sonography machine looks a bit like a computer with a microphone attached—almost like a Karaoke machine. Usually, the sonography machine is rolled right up to the bedside.

What to Wear

Wear something comfortable and easy to remove to your sonogram appointment. In most cases, you will have to expose only the skin that the technician needs access to. An abdominal ultrasound, for example, can be done while you wear pants and a shirt. You'll just have to pull your shirt up and away to expose your abdomen.

In the case of a transvaginal sonogram, you'll have to undress below the waist, including removing underwear.

Cost and Health Insurance

Sonography is a relatively inexpensive imaging test. It is covered by most insurance policies and might require pre-authorization, depending on the reason the healthcare provider ordered it in the first place.

A 3D or 4D sonogram is an elective test that some expectant parents get during pregnancy. The 3D image shows a three-dimensional rendering of the baby; 4D refers to an animated video rendering of the baby in utero, captured over time. These are known as entertainment tests and are not covered by most health insurance policies.

During the Test

In many cases, a sonogram is over before you know it. Here's what you can expect:

Throughout the Test

A sonogram is conducted by a single technician right at the bedside. The technician will ask you to undress enough to expose the area where the test will be performed and to lie down on the bed.

The technician will coat the transducer with conductive gel, which feels like lubricant jelly. If possible, depending on the tools and supplies available, the gel will be warm. Then the technician will slide the transducer over the skin, sometimes with firm pressure. Occasionally, the pressure can cause mild discomfort.

Using the transducer to point to areas of interest, the technician will use the computer to capture images and might use a mouse to drag lines across the screen. The lines help measure size, like a virtual yardstick. You should be able to watch the entire procedure and even ask questions throughout the procedure.

Post-Test

When the sonogram is over, the technician will usually provide a towel to wipe off the conductive gel. Once the technician confirms that all the necessary images have been captured, you will be free to get dressed. There are no special instructions or side effects to manage.

Interpreting the Results

It often takes a radiologist only a few minutes to interpret a sonogram. Typically, sonogram results are sent to the healthcare provider to share with a patient. So if you don't hear from your provider within the promised time frame, be sure to follow up.

If necessary, you can also request a copy of the radiologist's report and a disc containing the original images. For many expectant parents, this makes the entire trip worthwhile.

Summary

A sonogram is used to evaluate, diagnose, and treat a wide range of medical conditions, from lumps to kidney stones. Its most common usage, by far, is to check the development of a fetus and hear its heartbeat during pregnancy.

The live image that a sonogram captures is a painless procedure as well as a quick one. In many cases, a sonogram takes no more than 30 minutes from start to finish.

Follow your provider's instructions on whether you should eat or drink before the test, wear comfortable clothing, and the test will probably be over before you have a chance to fully relax.

A Word From Verywell

Sonography is one of the most noninvasive diagnostic medical tests available. It is a safe option for patients who need to know what is going on inside their bodies. If images are necessary, ask your healthcare provider if ultrasound is an option for you.