intravenous pyelogram
Meaning of intravenous pyelogram: The x-ray picture of the urinary tract outlined by dye that the kidneys have filtered out of the blood.
Definition of intravenous pyelogram
An intravenous pyelogram is the x-ray image produced after an iodine-containing dye is injected into a vein and filtered out by the kidneys. As the dye travels down the ureters into the bladder it outlines the whole drainage system, so a narrowing, a blockage or a stone appears as an interruption in that outline.
How is the image produced?
Iodine absorbs x-rays strongly, so anything holding it appears white on the film. The dye is injected into a vein in the arm, circulates, and is pulled out of the blood by the kidneys within minutes. A series of pictures is then taken as it gathers in the kidneys, runs down the ureters and fills the bladder. Nothing is injected into the urinary tract itself. The dye arrives there by the same route urine does, which is why the images show how well each kidney is working as well as what shape the tract is in.
What does it show?
| Finding | How it appears |
|---|---|
| Stone blocking a ureter | Dye stops abruptly, with swelling above it |
| Poorly working kidney | Dye appears late or faintly on that side |
| Tumor in the collecting system | A gap where dye should be |
| Structural variation | An unexpected shape or a duplicated system |
How does the image differ from the procedure?
The two words are often used as though interchangeable. Strictly, the pyelogram is the picture, while intravenous pyelography is the examination that produces it. The same distinction runs right through radiology, where the ending -gram names the record and -graphy names the act of making it.
Is it still used?
Far less than it once was. Computed tomography of the urinary tract gives the same information in greater detail, shows the organs around the tract at the same time, and can find a stone without any dye at all. That has displaced the older test in most places, particularly for sudden severe pain in the flank. It survives where computed tomography is unavailable and in some assessments of the shape of the collecting system. The cautions are unchanged: the dye can cause an allergic reaction and can worsen kidney function where the kidneys are already impaired, and an intravenous injection is needed every time.
Also known as
Used in a sentence
An intravenous pyelogram demonstrated obstruction at the lower end of the left ureter.
Good to know
The pyelogram is the image while pyelography is the examination that produces it, and computed tomography has replaced the test in most settings.
Word origin
Where “intravenous pyelogram” comes from
Pyelo- comes from the Greek pyelos, meaning a basin, used for the funnel-shaped part of the kidney, and -gram from gramma, something written.