Introduction

Post-operative imaging used to assess retrograde intra-renal surgery (RIRS) results affects stone-free rates (SFR). Imaging after RIRS may be unnecessary if surgeon&[prime]s endoscopic evaluation (EE) at the end of RIRS proved to be reliable._x000D_ The objective of our study was to assess the reliability of surgeon&[prime]s EE at the end of RIRS.

Methods

We made a retrospective analysis on all consecutive RIRS performed for renal stones from January 2009 to August 2016 and included in a prospectively maintained database. RIRS were performed with fiber optics instruments in one-day surgery under spinal anesthesia. A ureteral access sheath was used, laser lithotripsy was performed and significant fragments extracted. Multiple stones, stones > 2 cm and staged procedures were included. Surgeons recorded their EE particularly about the presence of significant residual fragments (SRF). Residual fragments were considered clinically insignificant (CIRF) if ≤ 4 mm. Primary endpoint of our study was the ability of EE made by an expert surgeon to exclude the presence of SRF at US at 2-3 weeks. Chi-square and Fisher tests were used for statistical analysis.

Results

294 RIRS were included. EE was available in 281 cases and US in 211. Mean stone size was 12.31 mm ± 4.87 mm (SD). In 68 cases (23.13%) stones were multiple. Post-operative US outcomes significantly differed from urologist&[prime]s EE in term of SRF, CIRF and SFR (p < 0.0001), independently from the number of RIRS performed per year by the surgeon (p < 0.001). 14% more patients were found stone-free (SFR 0U) at US compared to EE, 28% less were found to have CIRF and 14% more to have SRF. Table 1 shows how the concordance of EE and US outcomes varied in relation with surgeon&[prime]s expertise. In particular the difference in terms of SRF and CIRF decreased when EE was made by a surgeon performing ≥ 20 RIRS/year. The absence of SRF assessed at EE by a surgeon performing ≥ 20 RIRS/year was confirmed at US in 92% of cases. The probability to diagnose at US SRF not assessed at EE increased to 36% when EE was made by surgeons performing < 20 RIRS/year (OR = 6.4).

Conclusions

Post-operative US outcomes significantly differed from urologist&[prime]s EE. EE underestimated SFR and overestimated CIRF. SRF were underestimated at EE, but an expert surgeon reliably predicted the absence of SRF.

Funding

None