Renal cryotherapy in a sheep model; A feasability study

Purpose: This study was designed to evaluate the safety and efficacy of renal cryotherapy as a possible treatment of renal malignancy with preservation of renal parenchyma. Materials and Methods: Ten Merino sheep were anaesthetised and the right kidney was exposed through a retro-peritoneal approach. A 5 mm. cryotherapy probe (LCS 3000 Cryotec UK) was inserted into the lower pole of the kidney and freezing was undertaken to form an iceball 5 cm. in diameter. Results: There was no mortality and no complications were observed. A transient rise in creatinine was observed post-operatively. The sheep were euthenased at 4 weeks and at necropsy macroscopic examination revealed a contracted, fibrotic wedge shaped lesion of 3 cm in diameter. Histological examination of the ''cryolesion'' revealed a central area of coagulative necrosis and a 5 mm rim of partial necrosis with preservation of renal tubules. Conclusion: We conclude that renal cryotherapy is safe and can achieve effective renal necrosis in the sheep model.