MODIFICATION OF GUY’S SCORING SYSTEM FOR POST PCNL PREDICTION OF STONE FREE RATE AND COMPLICATION RATE

Abstract

Background Due to the wide variation in methods used by urologists to assess clinical and academic outcomes of PCNL, the SFR (Stone Free Rate) and complications can differ. Therefore, it is crucial to examine preoperative factors that influence these outcomes. To improve guidance for patients considering PCNL, nephrolithotomy scoring systems have been developed based on preoperative indicators, as inconsistent reporting of PCNL outcomes across different centres has been observed. Objectives To demonstrate the efficacy of integrating further possible patient and stone factors in this nephrolithmetry system provided, keeping the predictive value of this system as simple and reproducible as possible. Patients and MethodsData from one hundred consecutive cases of prone PCNL were collected after obtaining ethical approval. All cases were operated in Al-Sulaymaniyah Surgical Teaching Hospital and Shar Teaching Hospital between August 2021 and July 2022. Preoperative Guy’s scoring was applied by two endo-urologist to categorize all patients into four grades. The data included patients’ sociodemographic characteristics and stone parameters measured on preoperative non-contrast Computed tomography. ResultsThe mean age of patients was 44.85 years. The distribution of Guy’s stone score was as follows: G1=35 patients, G2=40 patients, G3=15 patients, and G4=10 patients. Tract length was <100mm in 51 cases and >100mm in 49 cases. Stone density was <1000 in 34 patients and >1000 in 66 patients. Postoperative residual stones were seen in 12 patients, and significant complications and blood transfusion were seen in 8 patients; all were more frequent with higher Guy’s scores. We found a statistically significant correlation between more than 100mm tract length and high postoperative residual stone by Chi-square test P-value 0.01. In addition, we observed strong relation between tract length and postoperative complication rates, though statistically insignificant. ConclusionWe suggest modifying Guy’s stone score by adding an expected tract length of more than 100mm to predict a higher residual stone rate and complication rate. Tract length can be added to Guy’s stone score and used as an upgrading factor by one grade whenever preoperative CT shows a tract length of more than 100mm.