Fluid dynamics within renal cavities during endoscopic stone surgery: does the position of the flexible ureteroscope and ureteral access sheath affect the outflow rate?

To evaluate the impact of ureteroscope position within renal cavities as well as different locations of the tip of the ureteral access sheath (UAS) on fluid dynamics during retrograde intrarenal surgery (RIRS).

A prospective observational clinical study was performed. Measurements with a flexible ureteroscope placed in the upper, middle and lower calyces were obtained with the tip of the UAS placed either 2 cm below the pyelo-ureteric junction (PUJ), or at the level of the iliac crest.

74 patients were included. The outflow rates from the middle and upper calyxes were statistically significantly higher compared to the lower calyx, both with the UAS close to the pyelo-ureteric junction and at the iliac crest. When the UAS was withdrawn and positioned at the level of the iliac crest, a significant decrease in outflow rates from the upper (40.1 ± 4.3 ml/min vs 35.8 ± 4.1 ml/min) and middle calyces (40.6 ± 4.0 ml/min vs 36.8 ± 4.6 ml/min) and an increase in the outflow from the lower calyx (28.5 ± 3.3 ml/min vs 33.7 ± 5.7 ml/min) were noted.

Our study showed that higher fluid outflow rates are observed from upper and middle calyces compared to lower calyx. This was true when the UAS was positioned 2 cm below the PUJ and at the iliac crest. Significant worsening of fluid dynamics from upper and middle calyces was observed when the UAS was placed distally at the level of the iliac crest. While the difference was statistically significant, the absolute change was not significant. In contrast, for lower calyces, a statistically significant improvement was documented.

World journal of urology. 2024 Apr 17*** epublish ***

Arman Tsaturyan, Etienne X Keller, Angelis Peteinaris, Faria-Costa Gabriel, Amelia Pietropaolo, Begona Ballesta Martinez, Vaseilios Tatanis, Eugenio Ventimiglia, Francesco Esperto, Tarik Emre Sener, Vincent De Coninck, Esteban Emiliani, B M Zeeshan Hameed, Michele Talso, Ioannis Mykoniatis, Lazaros Tzelves, Panagiotis Kallidonis

Department of Urology, Erebouni Medical Center, 0087, Yerevan, Armenia. ., EAU Young Academic Urologists (YAU) Urolithiasis and Endourology Working Group Arnhem, NL-6803, Arnhem, The Netherlands., Department of Urology, University of Patras, 26504, Patras, Greece., Department of Urology, Unidade Local de Saúde de Matosinhos, Matosinhos, Portugal., Department of Urology, University Hospital del Vinalopo, Alicante, Spain.