Comparison of renal parenchymal trauma after standard, mini and ultra-mini percutaneous tract dilation in porcine models.

OBJECTIVE

To evaluate whether reducing tract dilation diameter in PCNL (percutaneous nephrolithotomy) procedures results in minimizing of renal trauma of the percutaneous tract.

METHODS

A percutaneous renal access tract was established bilaterally to 11 pigs. Two pigs were euthanized immediately after the experiment, while nine pigs were sacrificed 1 month later. The percutaneous accesses were dilated up to 30Fr, 22Fr or 12Fr. The animals underwent a contrast-enhanced computer tomography immediately after the procedure and 30 days later. DMSA-scintigraphy with SPECT-CT was also performed. The kidneys of all animals were harvested for histological evaluation. The volume of scar tissue and the percentage of renal volume replaced by scar tissue were calculated.

RESULTS

Immediate post-procedural CT-scans revealed a significant difference in defect diameter among the three modalities. However, the scar volume calculated on CT-images and histopathology showed a significant difference only when 30Fr dilation was compared to 12Fr dilation. The percentage of scar volume was negligible in all cases, but there was still a statistical difference between 30 and 12Fr dilation. Dilation up to 22Fr revealed no statistical differences compared to the other two modalities. DMSA-scintigraphy showed no scar tissue in any case.

CONCLUSION

Dilation up to 30Fr may cause a significantly larger scar tissue on renal parenchyma compared to 12Fr dilation as it was shown on CT-images and microscopic evaluation, but based on the DMSA/SPECT-CT this difference seems to be insignificant to the renal function. The scar tissue caused by 22Fr dilation seemed to have no significant difference from the other modalities.