Authors' Response to Abourbih and Baldwin

To the Editor:

For the past 20 years, we have been enthusiastically watching flexible ureteroscopy (F-URS) become the major treatment option for most kidney stone cases. Enhanced optical quality, miniaturization of the endoscopes, improved tools and lasers, and introduction of ureteral access sheaths (UASs) have been major contributors of this success. Similar to Amplatz sheaths, they provide easy and repeated access to the collecting system as well as decreased intrarenal pressures due to continuous backflow of the irrigation solution. ^1,2

Increased intrarenal pressures have been an issue of interest since they may be the major source of complications behind F-URS. Due to histological changes caused by high intrarenal pressures, such as submucosal edema, congestion, increased permeability, and bacterial translocation, the renal physiology is altered and is prone to complications. ³ With UAS in place, the intrarenal pressures are 57% to 75% lower than that without UAS. ¹ Recently, in the Clinical Research Office of Endourological Society (CROES) Ureteroscopy Global Study, Traxer and colleagues demonstrated that UAS use can decrease complications. In this large series of patients undergoing F-URS, intraoperative complications were lower if an UAS is used. ⁴ Besides, it should be kept in mind while using an UAS that bigger UASs mean higher risk of ureteral damage. ⁵

We are actually facing the Goldilocks Paradox; we need an UAS that has just the right size. However, our results demonstrate the advantage of 10F/12F access sheaths in terms of intrarenal pressures. We have to be aware of what we can do with our instruments and also be sure if they are the right ones to use. Ureteroscopes are expensive, so are the disposable equipment when high numbers are considered. So, right investments bring success, low complication rates, and by this way, we can be cost-effective.