Effects of cryoablation on short-term development of urinary fistulas in the porcine kidney.

PURPOSE: To determine the effect of cryoablation on the collecting system in the porcine kidney and the possible development of pelvic injury or fistula.

MATERIALS AND

METHODS

Six kidneys from three domestic swine were utilized. Under MRI guidance, a 3-mm cryoprobe was placed percutaneously and advanced to a point adjacent to the collecting system. The tissue then was frozen to -40 degrees C for 4 to 6 minutes to create a 2-cm iceball. At 1 week postprocedure, the kidneys were harvested and underwent gross and microscopic examination for evidence of fistula formation or renal pelvis injury.

RESULTS

The procedures were performed without complications, although during placement of the probe in one pig, the collecting system was inadvertently entered. The diameter of the iceballs ranged from 2.0 to 2.5 cm. On pathologic examination, five of six of the kidneys, excluding the one noted above, were found to have no gross evidence of injury or fistula formation from the collecting system. Microscopic examination of the collecting system demonstrated necrosis extending up to the mucosa but no injury to the collecting system itself.

CONCLUSIONS

In this animal model, no evidence of damage to the renal collecting system secondary to freezing was found. Treatment of renal tumors that are close to the collecting system may be possible without damage to the collecting system.