Contrast and Radionuclide Cystography

Cystography uses X-rays and contrast agents (dyes) to study the bladder in detail. With it, urologists can check the structure of the organ while identifying disorders such as tumors infections and stones. Vesicoureteral reflux or urine backflow to the kidneys can often be identified with this study.

During past decades, urologists have added a nuclear version of this test, called a radionuclide cystogram, to their arsenal, particularly to study reflux (see radionuclide cystogram). Many physicians believe this technology is a better surveillance tool for tracing the migration of urine through the urinary tract because it uses less radiation exposure (some estimates suggest up to 200 times) than the conventional cystogram. It also does not rely on fluoroscopy, a radiological technique for visually examining the tissue, which contributes to the higher radiation exposures.

The doctor will insert a catheter through the patient's urethra and into the bladder. The dye or radioactive agent is then injected through the catheter into the bladder. X-ray pictures are taken at various stages of filling, from various angles, to visualize the bladder. Additional films are taken after drainage of the dye (see voiding cystourethrography). The procedure takes about an hour and a half and the patient may be asked to wait while films are developed. In surveying for vesicoureteral reflux, the urologist employs the same steps, using the radio-pharmaceutical, to collect continuous images every 10 to 15 seconds. While conventional voiding cystograms are still necessary to evaluate the male urethra for posterior valves and bladder trauma, the majority of reflux studies today are done effectively with radionuclide cystography.

While the risks are low, patients may experience urinary tract infections from the catheter, and, in rare circumstances, damage to the urethra, bladder or nearby structures can occur. Another risk is reaction to the contrast dye. Minor reactions include hot flashes, nausea and vomiting. These are usually treated successfully with antihistamines, drugs that reduce the effects of the body's inflammatory compound, histamine. In very rare circumstances, more severe complications — breathing difficulties, low blood pressure, swelling of the mouth or throat and even cardiac arrest — can occur.