Renal parenchyma injury after percutaneous nephrolithotomy tract dilatations in pig and cadaveric kidney models

Introduction: Miniaturization of instruments has changed the paradigms of percutaneous nephrolithotomy (PCNL). To date, however, few studies have analyzed the possible renal trauma generated by PCNL tract dilation. The purpose of this study is to evaluate and compare systematically the renal injury of all PNCL dilation techniques in pork kidneys (PK) and cadaveric kidney models (CK).

Material and methods: Twelve dilation devices were tested (from 4.8 to 30 French (Fr)) including micro- and mini- PCNL kits, the Alken dilation set, 20 and 30 ATM balloons and the Amplatz set. Each device was tested six times in PK and CK. Morphologic analysis of tract defects of the different models and dilators were made measuring the longest axis and the area of renal parenchymal damage.

Results: When comparing the PK and CK dilation tract areas to the device areas, major differences were seen with the 20 ATM 30 Fr balloon (p = 0.0001 and 0.008) respectively, the sequential Amplatz dilation to 30 Fr (p = 0.0005 and 0.0006) respectively, and the Alken 30 FR dilation (p = 0.012 and 0.02) respectively. The 30 Fr dilations were 32.76 mm² (mean) larger than the instruments themselves, while the ≤24 Fr dilations were 11.6 mm² (mean) larger than the instruments themselves.

Conclusions: When comparing devices and tract areas, the dilation tract area exceeded device area by 11.6 mm² at dilations up to 24 Fr vs. 32.76 mm² with dilations of 30 Fr. Overall, PK had significantly larger injuries than CK models.