An abdominal X-ray is a picture of structures and organs in the belly (abdomen). This includes the stomach, liver, spleen, large and small intestines, and the diaphragm, which is the muscle that separates the chest and belly areas. Often two X-rays will be taken from different positions. If the test is being done to look for certain problems of the kidneys or bladder, it is often called a KUB (for kidneys, ureters, and bladder).
X-rays are a form of radiation, like light or radio waves, that are focused into a beam, much like a flashlight beam. X-rays can pass through most objects including the human body. X-rays make a picture by striking a detector that either exposes a film or sends the picture to a computer. Dense tissues in the body, such as bones, block (absorb) many of the X-rays and look white on an X-ray picture. Less dense tissues, such as muscles and organs, block fewer of the X-rays (more of the X-rays pass through) and look like shades of gray on an X-ray. X-rays that pass mostly through air, such as through the lungs, look black on the picture.
An abdominal X-ray may be one of the first tests done to find a cause of belly pain, swelling, nausea, or vomiting. And other tests (such as ultrasound, CT scan, or intravenous pyelography) may be used to look for more specific problems.
Why It Is Done
An abdominal X-ray is done to:
- Look for a cause of pain or swelling in the belly or ongoing nausea and vomiting.
- Find a cause of pain in the lower back on either side of the spine (flank pain). An abdominal X-ray can show the size, shape, and position of the liver, spleen, and kidneys.
- Look for stones in the gallbladder, kidneys, ureters, or bladder.
- Look for air outside of the bowel (intestines).
- Find an object that has been swallowed or put into a body cavity.
- Confirm the proper position of tubes used by your doctor in your treatment, such as a tube to drain the stomach (nasogastric tube), a feeding tube in the stomach, a tube to drain the kidney (nephrostomy tube), a catheter used for dialysis, a shunt to drain fluid from the brain into the stomach (V-P shunt), or other drainage tubes or catheters.
How To Prepare
Before the X-ray test, tell your doctor if you are or might be pregnant. An abdominal X-ray is not usually done during pregnancy because of the risk of radiation exposure to your baby (fetus). Many times an abdominal ultrasound is done instead.
You may be asked to empty your bladder before the test. You may need to take off any jewelry that may be in the way of the X-ray picture, such as if you have a pierced belly button.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form( What is a PDF document? ).
How It Is Done
An abdominal X-ray is taken by a radiology technologist. The X-ray pictures are read by a radiologist. Some other doctors, such as emergency room doctors, can also look at abdominal X-rays to check for common problems, such as a blocked intestine.
You may need to take off all or most of your clothes. You will be given a gown to use during the test.
You will lie on your back on a table. A lead apron may be placed over your lower pelvic area to protect it from the X-ray. A woman's ovaries cannot be protected during this test because they lie too close to the belly organs that are X-rayed. A man's testicles can sometimes be protected during the test.
After the X-ray machine is positioned over your belly, you will be asked to hold your breath while the X-ray pictures are taken. You need to lie very still so the pictures are clear.
Many times, two pictures are taken: one while you are lying down (supine) and the other one while you are standing (erect view). The erect view can help find a blockage of the intestine or a hole (perforation) in the stomach or an intestine that is leaking air. If you are not able to stand, the X-ray may be taken while you lie on your side with your arm over your head.
An abdominal X-ray takes about 5 to 10 minutes. You will be asked to wait about 5 minutes while the X-rays are developed in case more pictures need to be taken. In some clinics and hospitals, X-ray pictures can be made right away on a computer screen (digitally).
How It Feels
You will feel no discomfort from the X-rays. The X-ray table may feel hard and the room may be cool. You may find that the positions you need to hold are uncomfortable or painful, especially if you have an injury.
There is always a slight chance of damage to cells or tissue from radiation, including the low levels of radiation used for this test. But the chance of damage from the X-rays is usually very low compared with the potential benefits of the test.
For example, the radiation exposure from a chest X-ray is about equal to the natural radiation exposure received during a round-trip airline flight from Boston to Los Angeles (Montreal to Vancouver) or 10 days in the Rocky Mountains (Denver, Colorado).
An abdominal X-ray takes a picture of structures and organs in the belly (abdomen). This includes the stomach, liver, spleen, large and small intestines, and the diaphragm, which is the muscle that separates the chest and belly areas. In an emergency, the results of an abdominal X-ray are ready in a few minutes. Otherwise, a radiologist usually has the official X-ray report ready the next day.
The pictures made by the X-rays show that the stomach, small and large bowel, liver, spleen, kidneys, and bladder are normal in size, shape, and location.
No growths, abnormal amounts of fluid (ascites), or foreign objects are seen. Normal amounts of air and fluid are seen in the intestines. Normal amounts of stool are seen in the large intestine.
A blocked intestine may be seen because a portion of the intestine is larger than usual or areas in the intestine have abnormal amounts of air or fluid in them.
A collection of air inside the belly cavity but outside the intestines (caused by a hole in the stomach or intestines) may be seen.
The walls of the intestines may look abnormal or thick.
The size, shape, or location of the bladder or kidneys may be abnormal. Kidney stones may be seen in the kidney, ureters, bladder, or urethra.
In some cases, gallstones can be seen on an abdominal X-ray.
Abnormal growths, such as large tumors, or ascites may be seen.
A foreign object is seen or a medical device looks abnormal or out of position.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Being pregnant. If a view of a pregnant woman's belly is needed, an ultrasound test may be done instead.
- Not being able to lie still and hold your breath during the test.
What To Think About
- Your X-ray results may be different from earlier test results because you were tested at a different medical center or you had a different kind of test.
- Certain results seen on an abdominal X-ray may mean more tests are needed to find the cause of the problem. These tests may include endoscopy, ultrasound, a computed tomography (CT) scan, a barium enema, or intravenous pyelography (IVP).
- An abdominal X-ray can't find certain problems, such as a bleeding stomach ulcer.
- A chest X-ray may be done at the same time as an abdominal X-ray. To learn more, see the topic Chest X-Ray.