Percutaneous bladder cryoablation in porcine model

PURPOSE: To demonstrate the morphologic changes of full-thickness bladder cryoablation utilizing contemporary percutaneous technology. MATERIALS AND METHODS: Cryoablation of the bladder wall was conducted in 24 pigs. The bladders were exposed laparoscopically and inspected cystoscopically. The animals underwent either extravesical (serosal) or transvesical (mucosal) approaches for the creation of the cryoablation lesion. Single or double freeze/thaw cycles were applied, and no bladder drainage was used. The bladder was evaluated for perforation, and histologic examination was undertaken to assess the extent of acute, subacute (2 weeks), or chronic (1 month) lesions. RESULTS: Cryoablation reliably produced a controlled transmural area of necrosis (both serosa and mucosa) by both techniques. The size and extent of the lesion were directly proportional to the duration of freezing and the type of cryoprobe used. The pathology report confirmed the full-thickness coagulative necrosis of muscle. Bladder perforation was not detected clinically or at autopsy. CONCLUSION: Cryoablation produces reliable zones of tissue destruction without bladder perforation. These preliminary data show the safety and feasibility for trials in the treatment of bladder tumors by laparoscopic, cystoscopic, or image-guided techniques.