IVP
Meaning of IVP: A timed series of x-rays that follows injected dye down the urinary tract to show where drainage has stalled.
Definition of IVP
IVP stands for intravenous pyelogram, an x-ray study of the kidneys, ureters and bladder taken after an iodine-based dye is injected into a vein. The kidneys filter the dye out of the blood and pass it into the urine, so pictures taken at set intervals trace its path and reveal any point where the flow of urine is blocked or distorted.
How does the test work?
The dye contains iodine, which blocks x-rays and appears bright white on the image. It is injected into an arm vein and reaches the kidneys through the bloodstream within seconds. Because the dye then travels the same route urine does, each picture taken over the following minutes outlines a different part of the system: first the filtering tissue, then the collecting spaces inside the kidney, then the ureters, and finally the bladder. A last image is often taken after the bladder has emptied.
What does it show?
Timing carries most of the information. A healthy kidney takes up the dye and clears it promptly, and the two sides normally keep pace with one another. A side that fills late, or holds the dye long after the other has drained, points to something obstructing flow below it.
| Finding | What it can mean |
|---|---|
| Delayed filling on one side | Obstruction of that kidney or its ureter |
| Widened collecting space | Urine backing up above a blockage |
| A gap in the dye column | A stone, clot or growth sitting in the way |
| A narrowed segment | Scarring, or pressure from outside the ureter |
How does it compare with other kidney imaging?
An ultrasound scan shows a swollen kidney but not always the level at which drainage stops. A CT study of the urinary tract gives the same functional account in far more detail, and it has taken over much of this work. What the older test still offers is a simple record of drainage over time using ordinary x-ray equipment. The full name, intravenous pyelography, describes the method exactly: dye into a vein, then images of the renal pelvis.
Why does the dye matter?
Iodine-based contrast is what makes the study possible, and it is also the source of its main hazards. Some people react to it, ranging from a warm flush and hives to a severe allergic reaction. The kidneys have to clear the dye, so a kidney already working poorly bears an added load. Because the dye is a source of iodine, it can also disturb thyroid function in susceptible people.
Also known as
Used in a sentence
The IVP showed delayed excretion on the left with dilation of the ureter above an obstructing stone.
Good to know
The study reports drainage over time rather than anatomy alone, and CT urography has replaced it for many indications; the iodine-based contrast carries a risk of allergic reaction and adds a load to impaired kidneys.
Word origin
Where “IVP” comes from
Pyelogram joins the Greek pyelos, meaning basin, a reference to the renal pelvis, with gramma, meaning something written or recorded.