In this presentation, we’re going to discuss some indicators and contraindications for
radiographic examination of the urinary system with contrast, as well as procedural and pre-exam
preparation recommendations.
Contrast Studies of the urinary system are performed to demonstrate the renal parenchyma,
and to do so effectively, contrast medium is needed, followed by imaging by either x-ray
or computed tomography.
Two filling techniques can be utilized to visualize the urinary system: Antegrade and
Retrograde.
Lower concentrations are required for bladder studies because of large large amount required
to fill bladder.
Higher concentrations are used for excretory urography.
Nonionic media less likely to cause an adverse reaction compared to ionic contrast media.
Preparation should all for clear demonstration of urinary system, and requires intestinal
tract to be free of gas and fecal material.
Bowel preparation is not attempted in infants and children.
Adult preparation depends on patient condition.
When time permits, low-residue diet for 1 to 2 days before examination should be planned.
A light evening meal on the day before examination, combined with a non–gas-forming laxative,
when indicated, the day before the examination.
Nothing by mouth after midnight the day of the examination and the patient should be
well hydrated.
Hydration is particularly important for patients with Diabetes, Multiple myeloma, and High
uric acid levels.
These conditions put patient at increased risk for contrast medium−induced renal failure
if dehydrated.
For retrograde urography, where contrast is injected via cannula inserted through the
urethra, into the bladder, and into the distal end of the ureter, the patient should drink
4 to 5 cups of water several hours before examination.
No preparation is usually required for examinations of the lower urinary tract.
A standard radiographic room sufficient for excretory urography and most retrograde studies
of the bladder and urethra.
A combination of cystoscopic and radiographic unit is needed for retrograde urographic procedures
that require cystography.
A tomography unit is required for infusion nephrourography.
Time-interval and body position markers should also be used for these procedures, and a sufficient
number of properly-sized image receptors should be available.
Make sure the emergency cart is nearby, and check to make sure it has been stocked.
You should always know the location of the cart in case of a contrast reaction where
seconds could mean a lot in the administration of drugs to counteract anaphylaxis.
Make sure you have all of your venipuncture supplies available as well, as long as any
equipment you may anticipate needing for motion control such as immobilization and ureteral
compression.
In excretory urography, compression is sometimes applied over the distal ends of the ureters.
The purpose of compression is to disrupt the flow of opacified urine into the bladder to
ensure filling of renal pelves and calyces.
Compression can be centered over level of anterior superior iliac spine (ASIS).
Apply and remove slowly to reduce patient discomfort caused by changes in intraabdominal
pressure.
Compression is contraindicated in patients with Urinary stones, Abdominal mass, Aortic
aneurysm, Colostomy, Suprapubic catheter, and Traumatic injuries.
Preliminary examination should include a Scout KUB.
Contrast and density will be the same as for abdominal radiographs with soft tissues of
the kidneys, the lower border of the liver, and the lateral margin of the psoas muscles
that must be defined.
It’s extremely important to inform patient of sensations caused by contrast injection.
This usually feels like a very warm, flush feeling that goes through your entire body,
and sometimes includes the taste of copper in the mouth.
It’s normal to feel this during the contrast injection and for a few moments after.
Exposures should be made at the end of expiration, unless otherwise requested.
Because of kidney excursion during respiration, it is possible to differentiate kidneys from
other shadows by making exposure on different phase of respiration.
Images should be marked if exposed on phase of respiration other than expiration.
The Scout anteroposterior (AP) radiograph, supine position, demonstrates location of
kidneys, their contour, and opaque calculi, if present and also serves to check gastrointestinal
(GI) tract preparation and exposure factors.