AUA 2018: Initial Clinical Testing of Ureteral Access Sheath Force Sensor to Prevent Ureteral Injuries

San Francisco, CA USA ( Zachary Valley from the University of California, Irvine (UCI), presented data on his team’s initial clinical findings using a ureteral access sheath force sensor (UAS-FS) during routine ureteroscopy procedure. As an introduction to his talk, Valley explained that ureteral injury is a major concern during ureteral access sheath deployment. However, the amount of force that results in clinical ureteral injury has yet to be defined.

For this study, 35 patients were recruited. Tamsulosin was given to 2/3rd of the patients for up to week prior to their procedure to induce a state of ureteral relaxation. During the procedure, ureteral access sheath deployment force was measured in using the UAS-FS under fluoroscopic control. Force readings were taken from the urethral meatus until the access sheath reached the area of the ureteropelvic junction/renal pelvis. The max limit of applied force was set at 8N based on a previous study. A 14/16F sheath was used in each initial attempt followed by a 12/14F and then a 9.5/11F sheath if 8N of force was reached during deployment. The ureter was evaluated at the end of each case and rated using the post-ureteroscopic lesion scale (PULS).

Following analysis, they found that in the 35 patients, 63% of deployments could successfully deploy a 16F ureteral access sheath at under 8N of force. The remaining cases had greater than 8N during 16F sheath deployment and required a 14F or 11F ureteral access sheath. For all the force recordings, the area most commonly recorded for maximum peak pressure was at the mid ureter and the mean PULS grade was 0.77. There was no significant difference between peak pressures and injuries in the tamsulosin and non-tamsulosin groups. Interestingly, there was only a solitary PULS 3 injury in a patient in whom three UAS insertions were serially tried 16F, 14F, and 11F with peak forces of 8.1N, 8.9N, and 5.0N. However, at their two months follow up there was no symptomatic nor radiographic evidence of a stricture.

Zachary Valley concluded that the UAS-FS was able to measure UAS insertion force in a reproducible fashion. He also added that by limiting the insertion force to < 5N resulted in a PULS score of ≤ 1 in all patients.

Presented by: Zachary Valley

Written by: Renai Yoon, Department of Urology, University of California-Irvine at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA