Chapter 90 Intravenous Pyelogram (Excretory Urography)
The intravenous pyelogram (IVP) is also called an excretory urography. This test assists with visualization of the following:
• Presence, size, configuration, and function of the kidneys, the renal pelvis, the ureters, and the bladder
• Renal function (assessed by timing the clearance of the contrast medium through the kidneys)
• Urinary or kidney abnormalities (e.g., tumors, polycystic kidney disease, renovascular hypertension, hydronephrosis, renal calculi, vesicoureteral reflux, or abscess)
• Distortions, strictures, scarring, and distention from obstruction
• Displacement of the kidneys, the ureters, or the bladder may indicate the presence of a mass or other abnormality.
Intravenous (IV) radiopaque contrast material is injected and assessed as it passes through the kidney, the ureters, and the bladder. The dye is filtered by the kidney and passes through renal tubules. Traditionally, visualization is achieved through a sequence of x-ray films taken at set intervals over the 30 to 45 minutes. Computed tomography (CT) and magnetic resonance imaging (MRI) are newer techniques being used for urography imaging.
Congenital abnormalities such as absent or displaced kidneys, horseshoe kidneys, and abnormalities of the ureter are detected by assessing size and position of the structures compared to normal. Retroperitoneal tumors are detected by assessing kidney displacement and/or compression of renal structures. Extrinsic or intrinsic tumors, cysts, stones, or scar tissue can be detected by assessing the flow of dye through the renal pelvis, the ureter, and the bladder. IVP after trauma to the urinary system may reveal urinary leakage outside the urinary system. Renal hematomas are detected by assessing kidney contours. If renal arterial blood flow is interrupted (e.g., renal artery blood clots, artery laceration), the contrast media may not be visualized or the clearance time may be significantly increased. If glomerular disease is present (e.g., glomerulonephritis), a delay in clearance time reflects the decreased glomerular filtration rate.
