CT Scan of the Kidney
What is a CT scan of the kidney?
CT scan is a type of imaging test. It uses X-rays and computer technology to make
images or slices of the body. A CT scan can make detailed pictures of any part of
the body. This includes the bones, muscles, fat, organs, and blood vessels. They are
more detailed than regular X-rays.
In a CT scan, an X-ray beam moves in a circle around your body. This allows many different
views of the same part of the body. The X-ray information is sent to a computer that
interprets the X-ray data and displays it on a monitor.
During some tests, you receive a contrast dye which may be given orally or through
a vein. This will make parts of your body show up better in the image.
CT scans of the kidneys can give more detailed information about the kidneys than
standard X-rays. This can provide more information related to injuries or diseases
of the kidneys. CT scans of the kidneys can help your healthcare provider find problems
such as tumors or other lesions, obstructive conditions, such as kidney stones, congenital
anomalies, polycystic kidney disease, buildup of fluid around the kidneys, and the
location of abscesses.
Your healthcare provider may need to do other related tests to diagnose kidney problems.
Why might I need a CT scan of the kidney?
A CT scan of the kidney may be done to check the kidneys for:
- Tumors or other lesions
- Obstructions such as kidney stones
- Polycystic kidney disease
- Defects you were born with
A CT scan is also useful when another type of exam, such as X-ray or physical exam,
is not conclusive. CT scans of the kidney may be used to evaluate the back part of
the belly. CT scans of the kidney may be used to help guide the needle placement in
After the removal of a kidney, CT scans may be used to locate abnormal masses in the
empty space where the kidney once was.
Your healthcare provider may have other reasons to recommend a CT scan of the belly.
What are the risks of a CT scan of the kidney?
You may want to ask your healthcare provider about the amount of radiation used during
the test. Also ask about the risks as they apply to you.
Consider writing down all X-rays you get, including past scans and X-rays for other
health reasons. Show this list to your provider. The risks of radiation exposure may
be tied to the number of X-rays you have and the X-ray treatments you have over time.
Tell your provider if:
- You are pregnant or think you may be. Radiation exposure during pregnancy may lead
to birth defects.
- You are allergic to or sensitive to medicines, contrast dyes, local anesthesia, iodine,
- You have kidney failure or other kidney problems. In some cases, the contrast dye
can cause kidney failure. People with kidney disease are more likely to have kidney
damage after having contrast dye.
- You take certain diabetes medicines. You may be at risk of developing metabolic acidosis.
This is an unsafe change in blood pH.
You may have other risks that are unique to you. Be sure to discuss any concerns with
your healthcare provider before the procedure.
Certain things can make a CT scan of the kidney less accurate. These include:
- Metal objects like surgical clips in your belly
- Barium in your intestines from a recent barium test
- Recent tests that used dye or other substances
How do I get ready for a CT scan of the kidney?
- Your healthcare provider will explain the procedure to you and give you a chance to
ask any questions.
- If your CT scan involves the use of contrast dye, you will be asked to sign a consent
form that gives permission to do the procedure. Read the form carefully and ask questions
if something is not clear.
- You may be told not to eat or drink anything for a few hours before the procedure.
- Tell the technologist if you have ever had a reaction to any contrast dye or if you
are allergic to iodine.
- Generally, you do not need to stop eating or drinking before a CT scan, unless a contrast
dye will be used. Your healthcare provider will give you special instructions ahead
of time if you need to fast.
- Tell the technologist if you are pregnant or think you may be.
- Tell the technologist if you have any body piercing on your chest or belly.
- Follow any other instructions your provider gives you to get ready.
What happens during a CT scan of the kidney?
You may have a CT scan as an outpatient or as part of your stay in a hospital.
The way the test is done may vary depending on your condition and your healthcare
Generally, a CT scan of the kidney follows this process:
- You will be asked to remove any clothing, jewelry, or other objects that may get in
the way of the procedure.
- If you are asked to remove clothing, you will be given a gown to wear.
- If you are having a procedure done with contrast, an IV line will be started in the
hand or arm for injection of the contrast dye. For oral contrast, you will be given
a liquid contrast to drink.
- You will lie on a scan table that slides into a large, circular opening of the scanning
machine. Pillows and straps may be used to prevent movement during the scan.
- The technologist will be in another room where the scanner controls are located. However,
you will be able to see the technologist through a window at all times. Speakers inside
the scanner will allow the technologist to talk to you and hear you. You will have
a call button so that you can let the technologist know if you have any problems during
the scan. The technologist will be watching you at all times and will be in constant
- As the scanner begins to rotate around you, X-rays will pass through your body for
short amounts of time. You will hear clicking sounds and whirring sounds, which are
- The X-rays absorbed by the body's tissues will be detected by the scanner and transmitted
to the computer. The computer will transform the information into an image to be interpreted
by the radiologist.
- It will be important that you stay very still during the scan. You may be asked to
hold your breath at various times during the scan.
- If contrast dye is used, you will be removed from the scanner after the first set
of scans has been completed. A second set of scans will be taken after the contrast
dye has been given.
- If contrast dye is used for your procedure, you may feel some effects when the dye
is injected into the IV line. These effects include a warm flushing sensation, a salty
or metallic taste in the mouth, a brief headache, and/or nausea. These effects usually
last for a few moments.
- You should tell the technologist if you feel any breathing difficulties, sweating,
numbness, or heart palpitations.
- When the procedure has been completed, you will be removed from the scanner.
- If an IV line was inserted, it will be removed.
- You may be asked to wait for a short period of time while the radiologist examines
the scans to make sure the images are clear.
The CT scan is not painful. You may have some discomfort or pain from lying still
during the test. This may be because of recent surgery or injury. The technologist
will use all possible comfort measures and do the scan as quickly as possible to minimize
any discomfort or pain.
What happens after a CT scan of the kidney?
If contrast dye was used during your procedure, you may be watched afterward for any
side effects or reactions to the contrast dye. These include itching, swelling, rash,
or difficulty breathing.
Tell your healthcare provider if you notice any pain, redness, or swelling at the
IV site after you go home. This could be a sign of infection or other type of reaction.
Otherwise, you do not need any special care after a CT scan of the kidney. You may
go back to your usual diet and activities unless your healthcare provider tells you
Your healthcare provider may give you other instructions, depending on your situation.
Before you agree to the test or the procedure make sure you know:
- The name of the test or procedure
- The reason you are having the test or procedure
- What results to expect and what they mean
- The risks and benefits of the test or procedure
- What the possible side effects or complications are
- When and where you are to have the test or procedure
- Who will do the test or procedure and what that person’s qualifications are
- What would happen if you did not have the test or procedure
- Any alternative tests or procedures to think about
- When and how will you get the results
- Who to call after the test or procedure if you have questions or problems
- How much will you have to pay for the test or procedure