The learning curve for retrograde intrarenal surgery: A prospective analysis.

INTRODUCTION: retrograde intrarenal surgery (CRIR) is an evolving tool. Its learning curve is not well established, despite the common use of flexible ureteroscopes today. Our aim is to estimate the number of procedures needed for one to perform RIRS consistently.

MATERIAL AND METHODS: a urology resident had his first 80 RIRS for nephrolithiasis analyzed quantitatively and qualitatively. The procedures were divided into 4 groups containing 20 surgeries each (I to IV), according to their order, for comparison.

RESULTS: there was no difference in stone sizes between groups. All qualitative variables varied significantly between groups (p<0.001), except between III and IV. In the quantitative analysis, there was a difference between groups I and IV in time for double-J catheter placement (p=0.012). There was an increasing difference in sheath placement time (p<0.001) and in total operative time (p=0.004). The time fot stone treatment (p=0.011) was significant only between groups I, II and III. There was difference in total sheath time only between groups I and III (p=0.023). Stone free status did not change between groups.

DISCUSSION: the differences between the qualitative and quantitative variables show the relation between number of surgeries performed and proficiency in the procedure. Intergroup comparisons show sequential optimization of parameters.

CONCLUSIONS: we found that 60 is a reasonable number of surgeries to be performed in order to reach the plateau of RIRSs learning curve.