(IVP, Intravenous Urography, IVU, Excretory Urography)
What is an intravenous pyelogram?
An intravenous pyelogram (IVP) is a type of x-ray that allows visualization of the kidneys and ureters after the injection of a contrast dye. The dye helps enhance the image on an X-ray film.
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 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.
Other related procedures that may be used to diagnose problems of the upper urinary tract include kidney, ureters, and bladder (KUB) X-ray, CT scan of the kidneys, renal ultrasound, renal angiogram, antegrade pyelogram, retrograde pyelogram, and renal venogram. Please see these procedures for additional information.
How does the urinary system work?
The body takes nutrients from food and converts them to energy. After the body has taken the food that it needs, waste products are left behind in the bowel and in the blood.
The urinary system keeps chemicals, such as potassium and sodium, and water in balance, and removes a type of waste, called urea, from the blood. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys.
Other important functions of the kidneys include blood pressure regulation, and the production of erythropoietin, which controls red blood cell production in the bone marrow.
Urinary system parts and their functions
Two kidneys - a pair of purplish-brown organs located below the ribs toward the middle of the back. Their function is to:
Remove liquid waste from the blood in the form of urine
Keep a stable balance of salts and other substances in the blood
Produce erythropoietin, a hormone that aids the formation of red blood cells
Regulate blood pressure
The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule. Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.
Two ureters - narrow tubes that carry urine from the kidneys to the bladder. Muscles in the ureter walls continually tighten and relax forcing urine downward, away from the kidneys. If urine backs up, or is allowed to stand still, a kidney infection can develop. About every 10 to 15 seconds, small amounts of urine are emptied into the bladder from the ureters.
Bladder - a triangle-shaped, hollow organ located in the lower abdomen. It is held in place by ligaments that are attached to other organs and the pelvic bones. The bladder's walls relax and expand to store urine, and contract and flatten to empty urine through the urethra. The typical healthy adult bladder can store up to two cups of urine for two to five hours.