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Kidney, Ureter, and Bladder (KUB) X-Ray Study

A kidney, ureter, and bladder (KUB) study is an X-ray study that allows your doctor to assess the organs of your urinary and gastrointestinal systems. Doctors can use it to help them diagnose urinary disorders and causes of abdominal pain. They can also use it to help them determine the size and position of your bladder, kidneys, and ureter.

What is the purpose of a KUB study?

Doctors order a KUB study to identify abdominal pain that they haven’t diagnosed yet. People who have symptoms of gallstones or kidney stones may also be candidates for this study. Having a KUB study may help your doctor confirm a diagnosis. Someone who has swallowed a foreign object might also benefit from the study, which can help the doctor determine whether the object is in the stomach.

During the test, X-ray images are taken of the structures of your digestive system, including the intestines and stomach. The KUB procedure can help your doctor diagnose certain gastrointestinal conditions, such as:

  • an intestinal blockage
  • foreign objects in the stomach
  • certain tumors
  • kidney stones and certain types of gallstones

Your doctor can also use it after a procedure. For example, they can use it to confirm if a feeding tube or ureteral stent is in the correct location.

What are the risks of a KUB study?

A person is exposed to low levels of radiation during a KUB study. The risk of radiation exposure from an X-ray is considered minimal compared to the benefits of the information your doctor can gather from it.

If you’re pregnant or you have any medical conditions, tell your doctor before having this study. They may need to take special precautions or not perform this study at all.

If you take bismuth, your doctor may recommend you stop taking it for a few days before the test. Bismuth is used to treat diarrhea and heartburn and can interfere with abdominal X-ray imaging.

A KUB study has few if any risks. In some cases, lying in the correct position and holding still for the X-ray may cause minor discomfort.

How is a KUB study performed?

This study typically takes place in a radiology department or center. An X-ray technician performs it. The procedure can be done on an outpatient basis, or your doctor may order it if you’re already staying in the hospital.

Preparation for a KUB study is minimal. Before the study, you’ll change into a hospital robe or gown and remove all jewelry. The X-ray technician will explain the procedure, which involves these steps:

  1. The technician will ask you to remain in a certain position depending on which view of your organs your doctor would like see.
  2. A lead apron may be placed over parts of your body that aren’t going to be X-rayed. This apron protects certain body parts from the radiation that the X-ray machine emits.
  3. Once you’re in the correct position, you’ll need to remain still while the X-ray technician directs the X-ray machine at your body and takes the images.

In some cases, your doctor may need multiple views and you may need to move into another position for another image.

Understanding the results of a KUB study

X-ray results are usually available within a few minutes. Your radiologist will view the images and interpret the results. Results of a KUB study may show injuries to your stomach or intestines, fluid in your abdominal cavity, or a blockage of your intestines. In addition, results may show the presence of kidney stones or gallstones.

The X-ray technician will go over the results with your doctor and additional testing may be necessary for a complete diagnosis. Your doctor or nurse will inform you of the results. The X-ray technician isn’t qualified to interpret the results.


A KUB study is a safe and relatively harmless procedure that can give you and your doctor a look at your kidneys, ureters, and bladder. The study can help your doctor diagnose pain or a condition right away, or it may be a preliminary step toward a diagnosis.

Content licensed from:

Written by: MaryAnn DePietro
Medically reviewed on: Aug 05, 2016: Carissa Stephens, RN, CCRN, CPN

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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