When do we need flexible ureteroscopy during ureteroscopic lithotripsy (URSL) for ureteric stones?

Abstract

Introduction and objectives: To determine predictive factors for therequirement of flexible ureteroscopy (F-URS) when rigid ureteroscopy(URS) fails during URSL and to evaluate outcomes of URSL by rigidURS and F-URS.Materials and methods: Operative record of URSLs performed from2012 to 2016 in our institution were reviewed. In 40 patients, rigidURS was not able to access the ureteric stone and stone fragmentationwas achieved by flexible URS. Patient demographics, stonecharacteristics, complication and stone free rate were recorded.Comparative analysis with another group of 40 patients who hadsuccessful rigid URS in the same period was performed.Results: Patient demographics were comparable between the URS andF-URS group. Mean stone size was larger in the F-URS group(11.5 mm) than the URS group (8.3 mm, P < 0.05). 95% of the stonesin the F-URS group were upper ureteric stones as compared to 23% inthe URS group (P < 0.05). In univariate analysis, stone size, stonelocation, presence of hydronephrosis and presence of ureteric stentwere factors predicting failure of rigid URS. Upon multivariateanalysis, stone location and presence of hydronephrosis wereindependent predictive factors for requirement of F-URS. Comparedwith the rigid URS group, the F-URS group had longer operative time(80 min vs 36 min, P < 0.05) and lower stone free rate (68% vs 95%,P < 0.05). There was no difference in complication rate between thetwo groups.Conclusion: Upper ureteric stone and presence of hydronephrosiswere independent predictive factors for requiring F-URS during URSL.Flexible URS has equivalently low complication rate as rigid URS butthe operative time is longer with lower stone free rate.