The Gachon University Ureteral Narrowing score: A comprehensive standardized system for predicting necessity of ureteral dilatation to treat proximal ureteral calculi

PURPOSE For treating proximal ureteral calculi, treatment decision has been known still difficult to choose ureteroscopic lithotripsy (URS) or shockwave lithotripsy. The aims of our study are to identify the possible predictors for necessity of URS and to propose the Gachon University Ureteral Narrowing scoring system (GUUN score) as a helpful predictor. MATERIALS AND METHODS We evaluated 83 consecutive patients who underwent semirigid URS due to proximal ureteral calculi between April 2011 and February 2014 by a single surgeon. We reviewed patient characteristics and pre- and postoperative parameters and surgical records. We divided the patients into 2 groups (group 1, nondilation group; group 2, dilation group) according to whether or not balloon dilation was performed. A stepwise logistic regression was performed to identify the factors that predict dilatation. Receiver operating characteristic (ROC) curves were plotted and areas under the ROC curve (AUC) were calculated to GUUN score. RESULTS Mean patients' age and their stone size were 48.53±12.90 years and 7.79±2.57 cm, respectively. Significantly smaller stone size (p=0.009), lower stone density (p=0.005), and lower ureteral density differences between ureteral narrowing level and far distal ureter (UD) (p<0.001) were observed in group 1 (n=34) than in group 2 (n=49). GUUN score consists of age, stone size and UD (AUC, 0.938). Overall stone-free clearance rate was 85.5%. CONCLUSIONS We suggest that the GUUN score is an excellent scoring system to predict the necessity of ureteral dilatation for decision making whether or not to perform surgical manipulation.