A CT scan takes a series of x-rays that build up a three-dimensional picture of the inside of the body. The scan is painless and takes about 60 minutes (1 hour).
CT scans use a small amount of radiation, which is very unlikely to harm you and will not harm anyone you come into contact with.
You will be given instructions on how to prepare for the test. Before the test, you can usually eat and drink normally. You may be asked to empty your bladder just before the test.
You will be given an injection of a dye. The dye travels through the bloodstream to the kidneys. The doctor looks at the screen to see the dye passing through the kidneys and ureters. This helps the doctor see your bladder, ureters and kidneys more clearly.
The dye may make you feel hot all over for a few minutes. Some people have a stronger reaction to the dye.
Tell your doctor if you have asthma or an iodine allergy, because you could have a stronger reaction to the injection.
You should also tell your doctor if you have kidney problems or diabetes, particularly if you take metformin. You will need a blood test before the scan to check how well your kidneys are working.
You should be able to go home as soon as the scan is over.