Kidney, Ureter, and Bladder X-Ray Study

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Kidney, ureter, and bladder x-ray study


A kidney, ureter, and bladder x-ray study (KUB) is an abdominal imaging procedure that uses x rays to create an image of the kidney, ureter, bladder and surrounding areas.


A KUB is performed to obtain information about the kidney, ureter, and bladder. It may be used if an individual has abdominal pain but a physical examination, health history , and review of the symptoms do not make the cause of the pain clear. It is also used as the first diagnostic tool when a problem with the urinary or gastrointestinal tract is suspected. A KUB can be used to help detect kidney stones . A KUB may also be used after a procedure that has placed a medical device in the area of the kidney, bladder, or ureter to ensure that proper placement was achieved, and that no shifting of the device has occurred.


  • What are you looking for on the x-ray?
  • If an abnormality is found, what is the next step?
  • Are there any other diagnostic imaging procedures or tests that may help you make an accurate diagnosis?


Women who are pregnant should not have a kidney, ureter, and bladder x-ray study. There is no way in which the fetus can be protected from the x rays during the procedure because the fetus is located directly in front of the area being imaged. X rays, while safe in small amounts for adults, can negatively affect the growth and development of a fetus. If a patient believes that there is a chance she may be pregnant she should let the x-ray staff know so that they can provide a pregnancy test or reschedule the procedure for another time.

Certain things can interfere with the accuracy of the results of the KUN, or the clarity of the images. If an individual has had a barium x ray recently in the same area, the accuracy of the x ray may be diminished. In there are growths or masses present on the uterus or ovaries, the accuracy of the KUN may also be affected. The presence of gas, feces, or foreign objects in the intestines can interfere with the radiologist's ability to accurately read the KUN. Any movement during the actual taking of the x ray, in many cases including breathing, can cause a distortion on the x-ray making it difficult to read, and in some cases causing the KUN to need to be repeated.


The kidneys are a pair of bean shaped organs, each about the size of an adult fist, located just below the ribs, towards the back of the body. The kidneys filter waste products and extra water out of the blood, which are then excreted as urine. The ureters are small tubes that connect the kidney to the bladder. It is through the ureters that the excreted wastes and excess water travels from the kidneys. The bladder is triangle shaped and located in the lower portion of the abdomen. It is hollow, so that it can hold and store urine. The urine travels through the ureters and into the bladder, where it inflates the bladder. When an individual urinates the bladder contracts forcing the urine out. The urine travels out of the bladder through a tube called the urethra, and from which it is expelled from the body.

Before the KUN, the patient may be asked to remove all metal jewelry and accessories, and may be asked to change into a hospital gown. Then the patient is asked to lie down on his or her back on an adjustable table. An unexposed plate or piece of special x-ray film is placed under the patient's abdomen. The radiologic technician then adjusts a special x-ray machine so that it is just over the individual's abdomen. The technician may cover areas of the patient's body that are not being x-rayed with a lead apron. X rays cannot penetrate lead, so this protects the patient from being exposed to x rays unnecessarily. The patient may be asked to briefly hold his or her breath to minimize movement when the x ray is being taken. Movement can make an z-ray image unclear. The technician then steps behind a special protective wall, and takes the x ray. Although small amounts of x ray radiation are safe, radiologic technicians need to stay behind a protective barrier to protect them from being exposed to dozens of x rays or more each day.

When the technician takes the x-ray the x-ray machine emits a very short burst of x-ray radiation aimed at the patient's abdomen. This radiation travels quickly through the patient's body and hits the unexposed film under the patient. The image produced looks like a photographic negative on x rays the more dense a substance is, the whiter it shows up. Therefore very dense things, like bones, show up very brightly. After the x ray has been taken the technician may examine it to ensure that it is clear before the patient leaves to ensure there is no need to take an additional x ray.


No special preparation is usually required for a kidney, bladder, and ureter x-ray study. In general, patients can eat, drink, and take medications normally before the procedure.


No special aftercare is required for a kidney, ureter, and bladder x-ray study.


No complications are expected from a kidney, ureter, and bladder x ray. Although radiation is used during the procedure, it is a very small amount and areas of the body not being imaged are usually covered with a protective lead shield. Although excessive exposure to radiation can increase the risk of cancer , this is usually only a significant concert to the medical health professionals who work with x rays every day, and not for the patient who has a few x rays over the course of many years. Individuals who have chronic diseases that require regular x-ray imaging may want to ask their doctor about the risks of repeated exposure over time.


Normal results of a kidney, ureter, and bladder x-ray study show the kidneys, ureters, and bladder to be of normal size and shape and located in the expected position. No nodules or growths are detected. There are many ways in which a KUN can return abnormal results. The kidneys, bladder, or ureters may be shown to be enlarged, misshapen, or moved within the body. One or more growths may be observed. Kidney stones may be detected. In many cases the results of the KUN are not enough to make a diagnosis by themselves, but instead are combined with information about symptoms, health history, physical examination, and the results of other diagnostic imaging studies or diagnosis laboratory tests to produce an accurate diagnosis.

Caregiver concerns

A doctor determines the need for a kidney, ureter, and bladder x-ray study based on the symptoms, health history, and physical examination of the patient. The doctor or members of the x-ray team explain the procedure, how the equipment works, and answer any questions the patient may have. The x ray itself is taken by a radiologic technician. The x ray or x rays are reviewed by a radiologist, and the results, sometimes along with copies of the images, are sent to the doctor who ordered the test. The doctor the communicates the results to the patient and determines what, if any treatment or additional diagnostic procedures are necessary.



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Michaely, H.J, et al. “Functional Renal Imaging: Nonvascular Renal Disease.” Abdominal Imaging 32.1 (February 2007): 1–17.

Thomsen, H.S. “Imaging Patients with Chronic Kidney Disease: CIN or NSF?” La Radiologia Medica 112.5(August 2007): 621–626.


Association of Diagnostic Imaging Technologists, 13750 Crosstown Drive Northwest, Suite 108, Andover, MN, 55304-5855, (763) 213-8252, (763) 753-7463,

Robert Bockstiegel