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.