intravenous pyelography
Meaning of intravenous pyelography: The examination itself, in which timed x-rays follow dye through the kidneys and down into the bladder.
Definition of intravenous pyelography
Intravenous pyelography is an x-ray examination that maps the urinary tract after contrast dye is injected into a vein. Pictures are taken at set intervals while the kidneys filter the dye and it travels down the ureters into the bladder. The timing of each image indicates how well each kidney is working.
What happens during the examination?
A plain film is taken first, before any dye is given, because a stone containing calcium shows on that alone and later images can hide it. The dye is then given by intravenous injection into a vein in the arm. Films follow at intervals: an early one while the kidney tissue itself is stained, further images as the collecting systems and ureters fill, and a final one taken after the bladder has been emptied. A compression band is sometimes placed across the abdomen to hold dye in the upper tract for longer. The whole examination takes under an hour in most cases, and longer where one kidney is slow to excrete.
Why does the timing matter?
Each film answers a different question, and comparing the two sides is what makes an abnormality visible.
| Timing | What it shows |
|---|---|
| Before dye | Stones and the general outline of the tract |
| Immediately after | How well kidney tissue takes the dye up |
| Several minutes later | The collecting systems and ureters filling |
| After emptying the bladder | Whether urine is being left behind |
A kidney that stains late and drains slowly is either working poorly or obstructed, and the difference between the sides is usually clearer than either side alone.
What are the risks?
Iodine-based contrast can cause reactions ranging from warmth and nausea through rash to, rarely, a severe allergic response, so a previous reaction changes how the test is approached. The dye can also worsen kidney function where the kidneys are already impaired, particularly alongside dehydration or certain medicines. The examination uses ionizing radiation, so it is avoided during pregnancy where an alternative exists. None of these risks are peculiar to this test; they apply to contrast studies generally.
Has it been replaced?
In most settings it has. Computed tomography of the urinary tract provides the same information in more detail, images the surrounding organs at the same time, and detects stones without any dye. Ultrasound answers many questions with no radiation at all. The older examination remains useful where those are unavailable and in selected assessments of the collecting system, and the resulting intravenous pyelogram still turns up in older records.
Also known as
Used in a sentence
Intravenous pyelography was performed to assess the anatomy of a duplicated collecting system.
Good to know
The plain film taken before any dye matters, because contrast filling the tract can conceal a stone that was visible beforehand.
Word origin
Where “intravenous pyelography” comes from
Pyelo- comes from the Greek pyelos, meaning a basin, used for the funnel of the kidney, with -graphy from graphein, to write.