Urography (pyelography)

Reviewed by Dr Sarah Burnett, consultant radiologist and Mr John Macfarlane, consultant urological surgeon and Dr John Pillinger, GP

What is urography?
Urography is an X-ray examination used to check the kidneys and the tubes that drain them (ureters).

A special dye is used to reveal any differences between the kidneys, or other abnormalities. The examination may also be used to look at the size and shape of the bladder. It is often called an intravenous urogram or IVU.

When is an IVU used?
An IVU is the most common kidney X-ray and is used to investigate a wide range of problems including:

pain in the kidneys

suspected kidney stones

blood in the urine

suspected obstruction

suspected congenital (inherited) abnormalities.

How is an IVU done?
The patient may be asked to take a mild laxative prior to the test to empty the bowel, as a full bowel could obscure the X-ray pictures.

The patient lies down on an X-ray table. After an initial X-ray is taken of the kidney and bladder area, a dye is injected into a vein in the back of the hand or arm.

The dye passes through the bloodstream into the kidneys, fills the collecting system within the kidneys and then passes through the main tube to the bladder (ureter).

Further X-ray pictures are taken to track the movement of the dye - usually after five minutes, then 20 minutes and a final picture after emptying the bladder.

More X-rays may be needed to clearly show the site of any obstruction. Commonly, a compression device may be placed across the lower abdomen, this is not painful and helps to provide good quality pictures of the kidneys.

Retrograde urography is also an X-ray examination of the urinary system. It is usually performed as part of a telescopic examination of the bladder (cystoscopy), made under a general anaesthetic.

A small tube or catheter is led into the passage leading to the kidney. Dye is then injected directly through this tube to outline the channels within the kidney and the ureter.

Is an IVU dangerous?
There is a slight risk that patients may be allergic to the iodine in the dye.

People with an allergy, hay fever or asthma are at risk and an alternative investigation may be suggested, or a small dose of corticosteroids given to suppress the allergic response.

Diabetic patients on metformin need to stop taking this medicine 48 hours before an IVU.

Pregnant women are not advised to undergo an IVU unless the potential benefits outweigh the risks to the unborn foetus.

Anyone suffering from severe liver, heart or kidney diseases may be given special instructions by a specialist before undergoing the examination.