Login to Access Video or Poster Abstract: MP75-12
Sources of Funding: None

Introduction

Previous retrospective and prospective studies have shown surprisingly low stone free rates (SFR) (approximately 50%) after ureteroscopy (URS) using stringent computed tomography (CT) criteria, although the aggressiveness of fragment extraction was not always quantified. Our goal was to determine SFR by CT after URS and aggressive fragment retrieval, quantified by the number of ureteroscope passes through a ureteral access sheath (UAS).

Methods

We prospectively evaluated patients undergoing URS with laser lithotripsy at our institution from December 2015 to October 2016. UAS were used in all patients except those with distal ureteral stones. Every attempt was made to extract all stone fragments, regardless of size, after fragmentation. Patient demographics, stone number, size, and location, and the number of passes of the ureteroscope were recorded. SFR was determined using non-contrast CT scan approximately 8 weeks after the procedure. Stone free (SF) cohort was compared to the residual fragment (RF) cohort using the student&[prime]s T-test and the chi-squared test, and binary logistic regression identified factors associated with stone free status. Statistical significance was set at p < 0.05.

Results

In total, 104 patients (141 renal units) underwent URS, with 67 patients (84 renal units) completing radiographic follow up to date. Mean number of stones was 3.3 and mean aggregate stone size was 13mm. Our overall SFR was 55%, with a mean number of ureteroscope passes of 44 (range 1 - 164). On univariate comparison between the SF and RF cohorts, SF patients had fewer numbers of stones (2.4 vs. 4.3, p=0.001), smaller aggregate stone size (11 vs. 15mm, p=0.02), and a smaller proportion of renal or renal and ureteral stones (54% and 15% vs. 66% and 26%, respectively, p=0.003). There were no significant differences in OR time, UAS size, or the number of ureteroscope passes (41 vs. 48, p=0.4) between groups. Binary logistic regression revealed no significant factors predictive of SF status.

Conclusions

SFRs by CT after URS are disappointingly low even with aggressive manual fragment retrieval. Larger sample size is likely to identify select cohorts of patients that benefit most from URS.

Funding

None