Response to Giusti et al. re “Prospective Evaluation of Bilateral Retrograde Intrarenal Surgery: Is It Really Safe?”

Dear Editor,

Bilateral same session retrograde intrarenal surgery (BSS-RIRS) is an appealing procedure; however, a few studies were published regarding its outcomes. The main limitation is that all of them were retrospectively conducted and only one matched with control group of unilateral RIRS. The lack of prospective studies on BSS-RIRS motivated our group to study this issue. We thank the interest and appreciate the comments by Giusti et al. regarding our article. ¹

Our study clearly presented the positive aspects of BSS-RIRS, namely less consumption of disposable devices and less operation room expenditure for renal unit. Moreover, we demonstrated similar outcomes for the first vs the second operated kidney of BSS-RIRS. In contrast, we demonstrated that BSS-RIRS had significantly more overall complications than unilateral RIRS (15.9% vs 39.9%, p < 0.001) and more emergency room visits (11.6% vs 34.8%, p = 0.026). ²

Although RIRS has been recognized as a low-risk procedure with minor complication profile, even mortality rates have been reported. ³ The alleged safety of BSS-RIRS by Giusti et al. was based on the evidence from two case series. However, the cited studies did not address directly BSS-RIRS but percutaneous nephrolithotomy. In contrast to the comments made by Giusti and colleagues, a retrospective study of unilateral RIRS by these authors reported overall complications of 29.1%, including grade 3 in 1.9% and grade 4 in 0.3%. ⁴ Overall complication of unilateral RIRS of our prospective study was 15.9%, without major complications. ² Minor complications are more likely to be missed in retrospective studies than in a prospective study because of forgetfulness. Therefore, a prospective and comparative study like ours has a higher level of evidence in this regard.

Major complications of RIRS are fortunately rare and small case series are unlike to report them. However, there are case reports of major complications of bilateral ureteroscopy as ureteral avulsion, intrarenal arteriovenous malformation, and anuric renal failure. ^{5 –7} Also, a fatal complication was reported on a retrospective study. ⁸

Giusti and associates credited the higher complication rate of BSS-RIRS to the number of renal units treated and to a “diffused effect” over time. However, this hypothesis should be tested in a proper study. Moreover, the complication rate of BSS-RIRS reported in our study would continue to be higher than unilateral RIRS even if divided by half. The same would happen to emergency room visits rate.

The consistent use of stent string was adopted in our study to warrant the same postoperative conditions for both groups, as it is a usual practice. Double-J displacement is a negative point for any RIRS and we agree that stent string should be avoided in BSS-RIRS because of its consequences, although we could not find this conclusion on previous reports.

We demonstrated a higher transient increase of creatinine in BSS-RIRS than in unilateral RIRS. Normal distribution of creatinine level was validated before comparison. Although mean creatinine levels remained within the normal range, this is an important finding because it alerts to a possible major complication in a patient with a borderline kidney function.

We do believe, as we presented in this prospective study, that BSS-RIRS is a valid way of saving resources and it can be safely performed. However, BSS-RIRS should not be encouraged as a standard of care for all patients. This may give a false sense of security. Also, other authors who previously published retrospective series of BSS-RIRS are experts in endourology. Rather, it should be performed only in properly selected patients by experienced surgeons.