Introduction

Primary access of the ureteral access sheath (UAS) is not always possible and often excessive force is exerted, thereby increasing the risk of ureteral injury. A randomized controlled trial was performed to investigate the efficacy of preoperative α-blockade on reducing UAS insertion forces (UASIF) and to appreciate the upper limit of UASIF to avoid ureteral injury.

Methods

From December 2015 to October 2016, 88 patients with ureteropelvic junction or renal pelvis stones planned for retrograde intrarenal surgery (RIRS) were prospectively enrolled. Patients were randomly assigned to a control group (n=37) or to an experimental group who received α-blockade with tamsulosin 0.4 mg q.d. for seven days prior to RIRS (n=39). Pre-stented patients were excluded from randomization (n=12). A homemade UASIF gauge was adapted to measure the maximal UASIF at the ureterovesical junction (UVJ) and the proximal ureter. The degree of mucosal injury was recorded.

Results

UASIF of the α-blockade group was significantly lower than controls at the UVJ (260.1±180.2 g vs. 524.2±237.5 g; p=0.017), however, not at the proximal ureter (367.2±175.2 g vs. 647.7±294.3 g; p=0.054). The α-blockade group exhibited comparable UASIF with the pre-stented group at the UVJ (260.1±180.2 g vs. 99.8±19.9 g; p=0.149) and the proximal ureter (367.2±175.2 g vs. 131.4±75.2 g; p=0.081). The rate of mucosal injury was lower in the α-blockade group compared to controls (p=0.028). Mucosal injury (≥grade 2) did not occur in cases with UASIF <600 g. UASIF was lower in females and patients aged ≥70 years compared to the counterparts (p=0.008 and p=0.021, respectively). Female gender and preoperative α-blockade were independent predictors of lower risks of ureteral injury.

Conclusions

Preoperative α-blockade mimics the effect of pre-stenting and reduces maximum UASIF and consequent risk of ureteral injury. If the UASIF exceeds 600g, the procedure could be terminated with stent placement and followed later by pre-stented RIRS.

Funding

none