What is an abdominal ultrasound?
An abdominal ultrasound (sonogram) is an imaging test used to assess the organs and structures in the belly (abdomen). These include the:
- Bile ducts
- Abdominal aorta
An abdominal ultrasound uses a handheld probe (transducer). It sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on the belly at certain locations and angles, the sound waves move through the skin and other body tissues to the organs and structures of the belly. The sound waves bounce off the organs like an echo and return to the transducer. The transducer picks up the reflected waves. These are then converted into an electronic picture of the organs.
Different types of body tissues affect how fast sound waves travel. Sound travels the fastest through bone tissue. It moves most slowly through air. The speed at which the sound waves are returned to the transducer, as well as how much of the sound wave returns, is translated by the transducer as different types of tissue.
Before the procedure, a clear, water-based gel is put on the skin. This lets the transducer move smoothly over the skin. It also helps remove any air between the skin and the transducer.
An ultrasound can also be used to assess blood flow in the belly. The transducer that does this contains a Doppler probe. The Doppler probe evaluates the speed and direction of blood flow in vessels by making the sound waves easy to hear. The degree of loudness of the sound waves indicates the rate of blood flow within a blood vessel. Absence or faintness of these sounds may mean there is a blockage of blood flow.
Why might I need an abdominal ultrasound?
Abdominal ultrasound may be used to assess the size and location of organs and structures in the belly. It can also be used to check the belly for conditions such as:
- Collections of fluid (cysts)
- Collections of pus (abscesses)
- Fluid buildup
- Clots in blood vessels
- Liver cirrhosis
- Abdominal aortic aneurysm
The size of the abdominal aorta can be measured by ultrasound. This may be done to detect an aortic aneurysm. This is a ballooning and weakening of the blood vessel. Stones in the gallbladder, kidneys, and ureters may also be found with ultrasound.
Abdominal ultrasound may be used to guide needles used to biopsy. A biopsy is the removal of a piece of tissue for testing. Abdominal ultrasound is also used to drain fluid from a cyst or a pus-filled infection (abscess).
This test can be used to assess blood flow in the belly.
There may be other reasons for your healthcare provider to advise an abdominal ultrasound.
What are the risks of an abdominal ultrasound?
There is no radiation used and generally no discomfort caused by moving the ultrasound transducer over the skin. No radiation or contrast dyes are used. So ultrasound may be safely used during pregnancy or in people with allergies to contrast dye.
There may be risks depending on your specific health condition. Discuss any concerns with your healthcare provider before the test.
Certain factors or conditions may interfere with the results of the test. These include:
- Severe obesity
- Barium in the intestines from a recent barium procedure
- Intestinal gas
How do I get ready for an abdominal ultrasound?
- Your healthcare provider will explain the test to you and you can ask questions.
- You may be asked to sign a consent form that gives your permission to do the test. Read the form carefully. Before you sign, ask questions if anything isn't clear.
- Any preparation before the test, such as fasting (not eating) or sedation (using medicines to make you sleepy), will be determined by the specific area to be examined. Your healthcare provider will give you instructions if needed.
- The gel placed on the skin during the test doesn't stain clothing. But the gel may not be fully removed from your skin afterward. So you may want to wear older clothing.
- Based on your health condition, your healthcare provider may request other specific preparation.
What happens during an abdominal ultrasound?
An abdominal ultrasound may be done on an outpatient basis. This means you go home the same day. Or it may be done as part of a hospital stay. Tests may vary depending on your condition and your healthcare provider's practices.
Generally, an abdominal ultrasound follows this process:
- You will be asked to remove any clothing, jewelry, or other objects that may interfere with the scan.
- If asked to remove clothing, you will be given a gown to wear.
- You will lie on an exam table. You will lie either on your side or on your back, depending on the specific area of the belly to be examined.
- A clear, water-based gel will be put on the skin over your belly.
- The transducer will be pressed against the skin and moved around over the area being studied.
- If blood flow is being assessed, you may hear a whoosh, whoosh sound when the Doppler probe is used.
- Once the test is done, the gel will be wiped off.
The abdominal ultrasound test itself causes no pain. But having to lie still or flat for the test may cause mild discomfort. And the gel may feel cool and wet. The technologist will use all possible comfort measures. They will complete the test as quickly as possible to reduce any discomfort.
What happens after an abdominal ultrasound?
There is no special care needed after an abdominal ultrasound. You may go back to your normal diet and activities unless your healthcare provider tells you differently.
Your provider may give you other instructions after the test, depending on your particular situation.
Before you agree to the test or the procedure, make sure you know:
- The name of the test or procedure
- The reason you are having the test or procedure
- What results to expect and what they mean
- The risks and benefits of the test or procedure
- What the possible side effects or complications are
- When and where you are to have the test or procedure
- Who will do the test or procedure and what that person’s qualifications are
- What would happen if you did not have the test or procedure
- Any alternative tests or procedures to think about
- When and how you will get the results
- Who to call after the test or procedure if you have questions or problems
- How much you will have to pay for the test or procedure