What is an intravenous pyelogram (IVP)?
An intravenous pyelogram, also called intravenous urography, is a diagnostic x-ray of the kidneys, ureters, and bladder. When a contrast dye is injected intravenously (IV), the urinary tract will show up very clearly, which is not seen on regular x-rays. An intravenous pyelogram may be done for many reasons, including the following:
- to detect kidney tumors
- to identify blockages or obstructions of the normal flow of urine
- to detect kidney or bladder stones
- to establish if the prostate gland is enlarged
- to detect injuries to the urinary tract
As the contrast dye moves into and through the kidneys, ureters, and bladder, x-rays taken at short intervals can capture its movement. A delay in the contrast dye moving through the urinary system may indicate an obstruction (blockage) in the kidney's blood flow or poor kidney function.
A radiologist can then assess the function and detect abnormalities of the urinary system. This test is usually ordered as one of the first tests in cases of suspected kidney disease or urinary tract disorders.
What is an X-ray?
X-rays use invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs on film or digital media. X-rays are made by using external radiation to produce images of the body, its organs, and other internal structures for diagnostic purposes. X-rays pass through body structures onto specially-treated plates (similar to camera film) or digital media and a "negative" type picture is made (the more solid a structure is, the whiter it appears on the film).
IVP may be performed at the same time as a computed tomography (CT) scan of the kidneys (also called nephrotomography). This test, like the IVP, is performed after contrast dye has been injected, but unlike a standard x-ray, provides images of layers or "slices" of the kidney.
As newer technologies are developed, other procedures such as CT, MRI, and ultrasound (high-frequency sound waves) are often used instead of IVP.
How are intravenous pyelograms performed?
Intravenous pyelograms are usually performed on an outpatient basis, although they can be part of inpatient care. The patient may be asked to take a laxative to cleanse the bowel before the examination.
Although each facility may have specific protocols in place, generally, an intravenous pyelogram procedure follows this process:
- The patient will be positioned on the x-ray table.
- A preliminary x-ray will be taken.
- An intravenous (IV) line will be started in the hand or arm for injection of the contrast dye.
- The radiologist will inject the contrast dye into the vein in the arm.
- During the injection of the contrast dye, the patient may feel warm and become flushed, only for a minute or so. This reaction is normal.
- Rarely, patients may experience an allergic reaction to the contrast dye, resulting in persistent itching or possibly hives. These symptoms are easily treated with medication.
- X-rays will be taken at intervals after the dye has been injected.
- At times the patient may have to change positions as the x-rays are taken.
- The patient will be asked to empty the bladder.
- A final x-ray will be taken after urination to determine the amount of contrast dye remaining in the urinary tract.