What Is a Kidney Ureter Bladder X-Ray Study?

Medically Reviewed on 1/29/2021

A kidney, ureter, and bladder (KUB) X-ray is a diagnostic test that can detect kidney stones and diagnose urinary tract disorders.
A kidney, ureter, and bladder (KUB) X-ray is a diagnostic test that can detect kidney stones and diagnose urinary tract disorders.

A kidney, ureter, and bladder (KUB) X-ray is a diagnostic test that is used for detecting kidney stones and diagnosing multiple disorders of the urinary tract. This diagnostic examination is usually done by injecting contrast media in your veins.

A KUB X-ray evaluates the urinary tract before other procedures are performed. Basic information regarding the kidney size and shape and position of the ureters and bladder is obtained with a KUB X-ray. The presence of calcification in the kidneys or ureters may point to stones in the urinary system. 

The doctor may also recommend a KUB X-ray to assess how quickly and efficiently the patient's system is able to handle the urinary waste. This exam can enable the radiologist to detect problems within the urinary tract resulting from an enlarged prostate or even a tumor in the kidney, ureter, or urinary bladder. 

In children, these tests often reveal constipation, which can contribute to urinary incontinence or help locate possible kidney stones.

The test is usually done on an outpatient basis, and the process is outlined below:

  • The patient is positioned on the table, and still X-ray images are taken. A contrast material is then injected, usually in a vein in the patient's arm, followed by additional still images.
  • The patient may need to stay very still and may be asked to keep from breathing for a few seconds while the X-ray is taken to reduce the possibility of a blurred image.
  • Because the contrast material is processed by the kidneys, a series of images are taken to determine the actual size of the kidneys and to capture the urinary tract in action as it begins to empty.
  • The technologist may apply a compression band around the body to better visualize the urinary structures leading from the kidney.
  • X-rays use invisible electromagnetic energy beams used to produce images of the internal tissues, bones, and organs on a film. External radiation produces images of the body, organs, and other internal structures for diagnostic purposes. X-rays pass through the body tissues onto specially-treated plates (similar to a camera film), and a “negative” picture is produced (the more solid a structure is, the whiter it appears on the film).
  • When the examination is complete, the patient will be asked to wait until the radiologist determines that all the necessary images have been obtained.
  • This study is usually completed within an hour. However, because some kidneys empty at a slower rate, the exam may last up to 4 hours.

While the X-ray procedure itself causes no pain, the manipulation of the body part being examined may cause some discomfort or pain, particularly in the case of a recent injury or an invasive procedure, such as a surgery. The technician will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain. 

Generally, you can resume your daily activities as soon as you have finished the scans. However, your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

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Medically Reviewed on 1/29/2021
References
Kidneys, Ureter, and Bladder (KUB) Imaging: https://emedicine.medscape.com/article/2165400-overview