Development and validation of a simple stone score to estimate the probability of residual stones prior to percutaneous nephrolithotomy.

Background: The aim of the present study was to develop and internally validate a simple stone score (SSS) to estimate the probability of clinically significant residual fragments (CSRF) prior to percutaneous nephrolithotomy (PNL).

Methods: The files of 1170 PNL procedures between January and December 2015 were evaluated. CT-derived stone characteristics were examined.