Unlike a kidneys, ureters, and bladder x-ray (KUB), which is a plain (that is, noncontrast) radiograph, an IVP uses contrast to highlight the urinary tract.
In IVP, the contrast agent is given through a vein (intravenously), allowed to be cleared by the kidneys and excreted through the urinary tract as part of the urine.
[6] They may also be able to show evidence of chronic scarring due to recurrent urinary tract infections,[5] and to assess for cysts[6] associated with polycystic kidney disease.
An injection of X-ray contrast medium is given to a patient via a needle or cannula into the vein,[7] typically in the antecubital fossa of arm.
To visualize the bladder correctly, a post micturition X-ray is taken, so that the bulk of the contrast (which can mask a pathology) is emptied.
This procedure is carried out on patients who present to an Emergency department, usually with severe renal colic and a positive hematuria test.
In this circumstance the attending physician requires to know whether a patient has a kidney stone and if it is causing any obstruction in the urinary system.
In pyelography, compression involves pressing on the lower abdominal area, which results in distension of the upper urinary tract.
[7] Antegrade pyelography is the procedure used to visualize the upper collecting system of the urinary tract, i.e., kidney and ureter.
It is done in cases where excretory or retrograde pyelography has failed or contraindicated, or when a nephrostomy tube is in place or delineation of upper tract is desired.
A retrograde pyelogram may be performed to find the cause of blood in the urine, or to locate the position of a stone or narrowing, tumour or clot, as an adjunct during the placement of ureteral stents.
[13] Before the procedure, a person is usually asked to complete a safety check assessing for potential risks, such as pregnancy or allergy.
[5] 10 ml of contrast[14] is usually injected during cystoscopy, which is where a flexible tube is inserted into the bladder and to the lower part of the ureter.
In the developed world, however, it has increasingly been replaced by contrast computed tomography of the urinary tract (CT urography), which gives greater detail of anatomy and function.