Introduction

All modern flexible ureteroscopes have a deflection of at least 270°, but approaching a difficult lower pole acute angled calyx can still be very difficult. The aim of our study was to find which ureteroscopes are better when dealing with a sharp angled calyx and to compare the deflection of the last few centimetres (cm) of the ureteroscope tip.

Methods

Using a training model for flexible ureteroscopy (K-Box®, Porges-Coloplast), we identified an acute angle calyx and we tried to access it with 9 different ureteroscopes (BOA vision and COBRA vision, Richard Wolf®; FLEX X2 and FLEX Xc, Karl Storz®; LithoVue, Boston Scientific®; URF-P5, URF-P6, URF-V and URF-V2, Olympus®). _x000D_ Passing the scope through a 10/12 Fr ureteral access sheath respectively (using ReTrace, Coloplast sheath) (except 12/14 Fr sheath for COBRA vision), with the tip out at 1 cm, 2 cm, 3 cm and 4 cm, we measured the maximum tip deflection for every ureteroscope.

Results

All optical ureteroscopes (URF-P5, FLEX X2) except the URF-P6 were able to access the sharp angled calyx. Except FLEX Xc, none of the digital ureteroscopes reached the difficult calyx._x000D_ _x000D_ All optical ureteroscopes had better end-tip deflection compared to the digital scopes with the exception of FLEX Xc, which was as deflectable as the optical ureteroscopes.

Conclusions

Digital ureteroscopes tend to be more rigid and the last centimeters of their tip seems to be less flexible, possibly due to the size of the camera capsule. When approaching a difficult, acute angled lower pole calyx, it might be better to use a fibre-optic ureteroscope.

Funding

none