What is a KUB CT scan?

A KUB CT scan is an imaging test that makes use of x-rays to obtain images of a person’s kidneys, ureters and bladder. The scan is mainly used for diagnosing urolithiasis or kidney/urinary tract stones. However, it may also be used for detecting other kidney-related problems.

Unlike an x-ray, a CT scan provides detailed images of the body from various different angles. These images can be seen on an attached computer screen.

To get a clearer picture of the area to be scanned, doctors sometimes give a contrast dye to the patient. The dye may be given intravenously or orally. It binds to body tissues, making them appear distinctly on the screen.

(Read more: KUB and PVR ultrasound)

  1. Why is a KUB CT scan done?
  2. Who cannot have a KUB CT scan?
  3. How should I prepare for a KUB CT scan?
  4. How is a KUB CT scan done?
  5. How will a KUB CT scan feel like?
  6. What do the results of a KUB CT scan mean?
  7. What are the risks and benefits of a KUB CT Scan?
  8. What happens after a KUB CT scan?
  9. What are the other tests that can be done with a KUB CT Scan?

A CT scan is preferred in cases where the traditional x-ray method does not provide enough information and a more thorough examination is needed. A KUB CT scan may be performed by the doctor to check for any health problems of the kidneys like:

This scan may be also useful in guiding the needle for conducting a kidney biopsy.

Additionally, a KUB CT scan may be performed if the doctor suspects that you have the symptoms of kidney or urinary bladder stones. Symptoms of kidney or bladder stones include:

A non-contrast KUB CT scan is usually performed to detect renal calculi while a contrast dye may be injected during a KUB CT scan to detect conditions that include inflammation or necrosis.

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Due to certain side effects associated with radiology tests, you must inform the doctor beforehand if:

  • You are pregnant or suspect that you may be pregnant (as exposure to radiation can cause birth defects)
  • You are allergic to contrast media, local anaesthesia or iodine.
  • You have kidney-related health issues as the use of contrast dye may lead to further kidney damage.
  • You take medicines for diabetes.

No prior preparations are needed for this test. However, if you need to have a contrast dye for the procedure, you will be asked to sign a consent form and to fast before the test.

Your doctor will explain the procedure to you and ask if you have previously had an allergic reaction to contrast media or iodine. Make sure to inform the doctor if you have any piercings in your chest or belly.

You will have to lie still for the scan. If you have anxiety or claustrophobia, talk to your doctor about it. He/she may give you a sedative to help with the scan.

You may require a hospital stay for the procedure. The scan will be done as follows:

  • Your doctor will ask you to remove any jewellery as these will interfere with the procedure.
  • The hospital staff will provide you with a comfortable gown to wear.
  • You will be asked to lie down on a scanning table with your arms positioned above your head. You will be asked to lie down still for the duration of the test. The technician may give use straps to help you avoid movement.
  • The scanning table will move into a larger circular opening of the CT scan machine.
  •  The technologist will be monitoring you through another room but will be able to communicate with you at all times. If you are feeling uncomfortable, nervous, sweating excessively, or having palpitations or breathing difficulties, you can inform him/her via a call button in the scanner.
  • The machine will collect data from the scan and use it to produce images on the attached computer screen.
  • If you need a KUB CT scan with contrast dye, a dye will be injected into your arm intravenously or given orally in the form of a liquid by taking you out of the scanner after the first set of scans. Then the second set of scans will be taken.
  • The intravenous line (if used) will be removed after the scan.
  • You may be asked to stay for some time so that the radiologist can be sure that the images obtained are clear.
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CT scan is a painless procedure. However, since you will be asked to stay as still as possible, you may find it slightly uncomfortable.

During the scan, you will hear clicking or whirring sounds being made by the machine.

If you are given a contrast dye, you may experience some side effects, such as:

  • A persisting salty or metallic taste in the mouth
  • A flushing sensation
  • Abdominal discomfort due to constipation and diarrhoea
  • Headache accompanied by nausea and vomiting
  • Redness or itching at the site where the needle was inserted

These side effects should subside quickly.

The CT scan images will be interpreted carefully by the radiologist to determine any abnormalities, such as:

The risks of a CT scan are:

  • If a contrast dye is used, there is a risk of a possible allergic reaction to it. Those on diabetes medication have an additional risk of kidney failure due to the dye.
  • Exposure to rays from CT scan in a pregnant woman may lead to birth defects in the baby.

The benefits of a CT scan are:

  • More detailed images and information as compared to the traditional x-ray procedure.
  • Quick results.
  • Can reduce the need for exploratory surgery in many cases by giving accurate results.
  • Improves the diagnosis and treatment of cancer.
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No special measures need to be taken after the test. You can return to your usual routine activities after the scan.

If you were given a sedative for the scan, you will have to request a friend or family member to drive you home.

If you were given contrast media during the test, you might have certain side effects such as swelling, itching or breathing problems. You may also have redness or swelling at the site of needle insertion. If you observe any of these symptoms, you should report them to the doctor.

The doctor may order other tests with or after the CT scan for an accurate diagnosis. These tests are:

  • Kidney biopsy
  • Kidney ultrasound
  • KUB x-rays
  • Angiogram or venogram of the kidneys

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.


  1. University of Rochester Medical Center [Internet]. University of Rochester. New York. US; CT Scan of the Kidney
  2. Cleveland Clinic [Internet]. Ohio. US; Bladder Stones (Bladder Calculi)
  3. American Kidney Fund [Internet]. Maryland. US; Kidney Stone Causes, Symptoms, Treatments, & Prevention
  4. Stanford Healthcare [Internet]. University of Stanford. California. US; Risks of Computed Tomography (CT) Scan
  5. Johns Hopkins Medicine [Internet]. The Johns Hopkins University, The Johns Hopkins Hospital, and Johns Hopkins Health System; Computed Tomography (CT or CAT) Scan of the Kidney Facebook
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