Presentation Authors: Stephanie Dresner*, Viacheslav Iremashvili, Sara Best, Sean Hedican, Stephen Nakada, Madison, WI
Introduction: Influence of renal anatomy on success rates for SWL has been evaluated in the literature with emphasis on lower pole anatomy. Influence of renal anatomy has been less well evaluated in the setting of ureteroscopy and laser lithotripsy for stone treatment despite acknowledgement that need for increased deflection of the ureteroscope in lower pole calices can present challenges intraoperatively. This study analyzed influence of infundibulopelvic angle of the lower pole on the outcomes of ureteroscopy and laser lithotripsy with respect to stone-free rate and need for reoperation.
Methods: We retrospectively analyzed 735 renal units undergoing retrograde flexible ureteroscopy with laser lithotripsy between January 2009 and December 2016. All cases were performed at a single institution. No exclusion criteria was applied with regard to preoperative stone location. Success was defined as no evidence of residual stone fragments on follow-up imaging with KUB or renal US within 2 months of surgery. Failure was defined as any stone present on follow-up imaging. Infundibulopelvic angle of the lower pole was measured on intraoperative retrograde pyelogram as described by Elbahnasy et al. Univariate and multivariate analyses of factors contributing to stone-free rate were performed. Secondary outcomes included repeat same-sided surgery within 6 months of the original surgery.
Results: Of the 735 cases evaluated, 243 cases had a retrograde pyelogram stored in PACS sufficient for IPA interpretation. 122 (50%) of those patients were female. 127 patients (52.3%) were stone free on follow up imaging, while 116 (47.7%) had residual stone burden. 144 (59%) patients had less than or equal to 3mm stone burden on follow-up imaging. In multivariate analysis adjusting for stone size, stone-free status was found to be statistically significantly associated with greater IPA (p < 0.0001). An obtuse IPA (>90 degrees) was also significantly influential on stone-free status. IPA and stone size were both found to be significantly influential on need for repeat surgery within 6 months (p < 0.05).
Conclusions: Our data showed IPA < 90 degrees and larger preoperative stone size negatively affect stone-free rate and need for repeat surgery following retrograde flexible ureteroscopy with laser lithotripsy for treatment of renal stones.