About a CT urogram
A CT urogram (CTU) is a CT (computed tomography) scan of the whole urinary tract: the kidneys, the ureters (the tubes that carry urine to the bladder) and the bladder. Unlike a CT KUB, it uses an injection of contrast dye. Pictures are taken at different times as the dye passes through the kidneys and into the urine, so the inside lining of the urinary tract can be seen in detail.
The main use of a CT urogram is to investigate blood in the urine (haematuria), especially visible blood. There are many causes, including infections, stones and an enlarged prostate, but blood in the urine can also be a sign of cancer of the kidney, ureter or bladder, so it should always be checked. A CT urogram is usually done alongside a cystoscopy (a camera test of the bladder), as small growths in the bladder lining can be missed on CT.
A CT urogram may also be used to look at:
- growths in the kidneys and the lining of the urinary tract
- stones, blockages and narrowing of the ureters
- problems with the shape of the kidneys and ureters that people are born with
- the urinary tract after surgery or injury
What happens during the scan
You may be asked to drink water before the scan so that your bladder is comfortably full. A small cannula is placed in a vein in your arm. You lie on your back on the scanner bed, and one set of pictures may be taken before the contrast is given. Contrast is then injected, and further pictures are taken at set times as it passes through the kidneys and into the bladder; some centres give the contrast in two parts. You may need to wait on or near the scanner between sets of pictures. The radiographer controls the scanner from the next room, but can see, hear and talk to you throughout.
For some CT scans, an injection of contrast dye is given through a small cannula in a vein, usually in your arm or hand, to make blood vessels and organs show up more clearly. CT contrast contains iodine. As it goes in you may feel warm and flushed, notice a metallic taste, or feel as if you are passing urine; these feelings pass within a minute or two. Allergic reactions are uncommon, and you may be asked to wait for up to 30 minutes afterwards. Where contrast is needed, it is charged separately.
Is CT safe?
CT uses X-rays, which are a type of ionising radiation. Because pictures are taken more than once as the contrast moves through, the dose is higher than for a single CT of the abdomen and pelvis (about 10 mSv). Centres use techniques to keep the number of scans and the dose as low as possible. The risk from a single scan is very small, and every CT scan is checked by a radiologist or radiographer to make sure the benefit of the scan outweighs the risk, as required by the Ionising Radiation (Medical Exposure) Regulations. If you have had other CT scans recently, tell us when you book.
What the scan can show
A CT urogram can help to look at:
- the cause of blood in the urine
- kidney growths and cysts
- growths in the lining of the kidneys, ureters and bladder
- stones and blockages
- narrowing of the ureters
- the shape and drainage of the kidneys
See a GP if you notice blood in your urine, even if it happens only once and there is no pain. Go to A&E if you have blood in your urine and cannot pass urine, are passing large clots, or feel very unwell.
Preparing for your scan
You may be asked not to eat for 2–4 hours before your scan, and to drink water in the hour beforehand so your bladder is full. You can usually take your normal medicines. Because contrast is used, you may be asked for a recent kidney blood test result. Upload any previous scan reports, urine test results and letters from your urologist when you book.
Wear loose, comfortable clothing without metal zips, poppers or buttons, and leave jewellery at home, as metal in the scan area can affect the pictures. You may be asked to change into a gown. Unlike MRI, CT is not affected by pacemakers or most metal implants, and the scanner is a short open ring rather than a tunnel, so it is usually easier for people who feel anxious in enclosed spaces.
Tell the team before your scan if you are, or might be, pregnant or breastfeeding, if you have kidney problems, diabetes (especially if you take metformin), asthma, thyroid problems or allergies, or if you have had a reaction to contrast dye before. If you need contrast, you may be asked for a recent kidney blood test result.
Frequently asked questions
What is the difference between a CT urogram and a CT KUB?
A CT KUB is a quick, low-dose scan without contrast, used mainly for stones. A CT urogram uses contrast and several sets of pictures to show the lining of the urinary tract, and is used mainly to investigate blood in the urine.
Will I still need a cystoscopy?
Usually, yes. A CT urogram is very good at showing the kidneys and ureters, but small growths in the bladder lining are best seen with a cystoscopy. Your urologist will advise you.
Does blood in my urine mean I have cancer?
Most people with blood in their urine do not have cancer. Common causes include infections and stones. It should always be checked by a doctor, as cancer is easier to treat when found early.
Do I need a referral?
Because CT uses radiation, each scan has to be justified by a qualified professional before it can go ahead. Upload a referral from your GP or consultant when you book if you have one. If you do not, select “no referral” and the scanning centre will review your request and confirm the next steps with you, which may include arranging a referral.
Sources
- NHS – Blood in urine
- BAUS – Blood in the urine (haematuria)
- NHS – Bladder cancer: diagnosis
- NICE NG12 – Suspected cancer: recognition and referral
- NHS – CT scan
- UKHSA – Patient dose information: guidance
The information on this page has been gathered from various sources and is provided for general information only. It is not medical advice. TOP MRI is not liable for the accuracy or completeness of this information. Please speak to your doctor or the scanning centre about your own situation.