LAUSR

I read the article ‘Comparison of suctioning and traditional ureteral access sheath during flexible ureteroscopy in the treatment of renal stones’ by Zhu et al. [1] with great interest. They compared safety and efficacy of a novel suctioning flexible ureteroscopy (fURS) technique with traditional ureterorenoscopy (tURS) for the treatment of renal calculi and found the novel technique superior to tURS in terms of operation time, postoperative first-day stone-free rate (SFR), postoperative fever and urosepsis. Additionally, I would like to highlight some issues. Increasing intrarenal pelvic pressure (IPP) during fURS is one of the major factors causing complications such as postoperative infection and hematoma [2]. In previous studies [3, 4], the diameter of the used suctioning ureteral access sheaths (UASs) was a bit larger than is in this study, 15F/11.5F vs 14F/12F. This might be a superiority of the UAS in this study to overcome the complications faced by using larger UASs [5]. However, the lack of an intelligent IPP monitoring system impairs the safety of this device. To control the IPP by manual twisting of the suctioning system is also not practical. Another issue that must be considered is irrigation of the renal unit with a 5F catheter using a syringe at the end of the stone fragmentation. I think it is impossible to control the IPP by this method which might result in papillary rupture. Additionally, this is also against the main principle of suctioning fURS. Finally, I would like to mention about the method of renal stone burden. The authors measured the maximal stone diameter on non-contrast computed tomography. Calculating the stone volume could be a more reliable tool in stone-size assessment such that the volume of stones of the same length might differ significantly [6].