Category: Clinical Stones: PCNL

MP26-2 - Does Sheath Size Matter: Time Utilization of Mini Versus Standard Tract Percutaneous Nephrolithotomy For Up To 3cm Renal Stones

Sun, Sep 23
10:00 AM - 12:00 PM

Introduction & Objective : The aim of this study was to objectively analyze the operative times and surgical outcomes for mini-percutaneous nephrolithotomy (mPNL) versus standard percutaneous nephrolithotomy (PNL) for stones of comparable sizes.


Methods : A prospectively maintained stone database was queried for percutaneous procedures performed between 7/2017 - 5/2018 for stones < 33mm (the largest stone treated by mPNL) conducted at a free standing ambulatory surgical center.  All procedure were done in prone positon with flexible retrograde ureteroscopy through an 11/13 Fr ureteral access sheath.  Percutaneous access was achieved with endoscopic and fluoroscopic guidance. Percutaneous stone treatment was performed through a 34/30 Fr (PNL) or 17.5/ 15.5 Fr (mPNL) sheath.  Stone free status was determined by either dual scope endoscopy plus ultrasound at < 1 month or CT scan < 1 week.  Patient, stone and surgical variables were collected including operative time, intracorporeal time (time from incision to removal of scope) and treatment time (time performing lithotripsy or stone removal).  Characteristics of stone-free patients (no fragment > 3mm) and surgical times were analyzed using t-tests, linear and logistic regression with p < 0.05.


Results : A total of 120 procedures were reviewed. Seventy three (61%) underwent PNL while 47 (39%) underwent mPNL.  One hundred eighteen patients (98%) had a ureteral stent placed and no nephrostomy tubes were used.  Patient and operative variables can be seen in Table 1.  Three patients had residual stone (2 patient from PNL, 1 patient from mPNL) of which one patient (from PNL cohort) underwent a second look ureteroscopy for residual stone.  Three patients required transfer to the hospital (1 from PNL, 2 from mPNL).  The fluoroscopy time had a significant impact on the total operative time (p < 0.005, 95%CI 0.192 – 0.396).  Access sheath size did not have a significant impact on total operative, intracorporeal or treatment time when taking stone size into account [p= 0.536, 95%CI (-6.08,11.62), p=0.067 95%CI (-0.428 ,12.6) & p=0.385, 95%CI (-2.87, 7.37) respectively].


Conclusions : Standard Tract PNL and mPNL are equally effective options in the management of renal stones up to 30mm in size with similar stone free rates and operative times.

Julio G. Davalos

Director Kidney Stone Program
Chesapeake Urology
Baltimore, Maryland

Mark V. Silva

Endourology Fellow
Chesapeake Urology
New York, New York

Mark V. Silva, MD
NYU Dept. of Urology
New York, NY

Jonathan Diah

Columbia University
New York, New York

Joel E. Abbott

Endourologist
Chesapeake Urology
Baltimore, Maryland