Impact of ureteral access sheath force of insertion on ureteral trauma: In vivo preliminary study with 7 patients.

BACKDROUND: Ureteral access sheaths (UASs) are commonly used in retrograde intra-renal surgery (RIRS). Despite their advantages, there is a risk of ureteral trauma during their placement and subsequent stricture following surgery. The aim of this study was to evaluate the UAS force of insertion (F01) during placement and its impact on ureteral trauma. METHODS: Seven female patients who underwent RIRS for kidney stones were included in the study. A digital force gauge (Chatillon DFX II; Ametek Test and Calibration Instruments, Largo, Florida, USA) was connected to the distal end of the UAS and the UAS FOI was continuously measured during insertion. UASs of different sizes were used and ureteral injury was evaluated under direct vision with the Post-Ureteroscopic Lesion Scale (PULS) score. RESULTS: Five pre-stented patients and 2 non-stented patients were included in the study. The size of the UASs used in non-stented patients was 9.5/11.5-F and 10/12-F, whereas one 11/13-F and four 12/ 14-F sheaths were used in the pre-stented patients. The highest maximal UAS FOI observed was 5.9 Newton (N) in a pre-stented patient with a 12/14-F UAS, where a second attempt was performed after initial failure. The lowest maximal UAS FOI was 0.91 N in a non-stented patient using a 9.5/11.5-F UAS. A semirigid ureteroscopy with a 7.8-F sheath was performed in this patient prior UAS placement. The PULS score was 1 in the 2 non-stented patients and 0 in all of the pre-stented patients. CONCLUSION: In this small cohort, a preoperative JJ stent seemed to protect the ureter, even with larger diameter UASs of 12/14-F. RIRS with a UAS is possible, but may cause low-grade ureteral trauma.