Is standard percutaneous nephrolithotomy still the standard treatment modality for renal stones less than three centimeters?

Objective: The aim of study was to compare the efficiency and safety of standard percutaneous nephrolithotomy (sPNL) and miniaturized percutaneous nephrolithotomy (mPNL) in lower calyx and/or pelvic stones smaller than three centimeters.

Material and methods: From October 2010 to August 2015, 108 mPNL and 176 sPNL procedures were performed for renal stones smaller than three cm and located in the lower calyx and/or renal pelvis. All patients were evaluated preoperatively with intravenous pyelography and/or computed tomography. Intraoperative parameters, post-operative results and complications were recorded. Postoperative success was defined as complete stone clearance and/or clinically insignificant residual fragments at 3rd month.

Results: Preoperative characteristics were similar between sPNL and mPNL groups except previous renal stone operation history and gender. The mean operation time was significantly shorter in the sPNL group (p<0.001). The mean hemoglobin drop was significantly less in the mPNL group (p=0.001), we found a 1.27±1.4 and 0.5±1.3 decrease in mean hemoglobin levels (mg/dL) in the sPNL and mPNL groups, respectively. Transfusion rate was 1.9% in mPNL and 5.6% in sPNL groups, and the difference was statistically significant (p=0.048). Only one patient in the sPNL group needed angiography and embolization. Postoperative JJ stent insertion rate was significantly higher in the mPNL group (p=0.03).

Conclusion: Both sPNL and mPNL are safe and effective surgical procedures for lower calyx and/or pelvis stones smaller than 3 cm. However, use of smaller caliber instruments was associated with a lesser hemoglobin drop and need for transfusion.