STONE DISEASE

Effect of ureteral access sheath on stone-free rates in patients undergoing ureteroscopic management of renal calculi
L’esperance JO, Ekeruo WO, Scales CD Jr, Marguet CG, Springhart WP, Maloney ME, Albala DM, Preminger GM
Comprehensive Kidney Stone Center, Division of Urology, Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
Urology. 2005; 66: 252-5

• Objectives: To evaluate the effect of ureteral access sheaths (UASs) on stone-free rates (SFRs) during ureteroscopic treatment of renal calculi. Several advantages of UASs during flexible ureteroscopy have been documented. However, no study has evaluated their impact on SFRs.
• Methods: We retrospectively reviewed all ureteroscopic cases for the management of renal stones performed at our Stone Center. Data were stratified according to the use or lack of use of the UAS. The groups were stratified by stone location within the kidney. Stone-free status was determined at 2 months postoperatively by either intravenous urography with tomograms or noncontrast renal computed tomography in patients with contrast allergies.
• Results: A total of 256 ureteroscopic procedures for the removal of renal calculi were performed between 1997 and 2003 (173 with UAS and 83 without). The groups were similar in age, sex, and stone burden. Stents were placed in nearly 80% of patients. The lower renal pole represented the most common presenting location. Stone displacement with a ureteroscopic basket for efficient fragmentation was necessary in 34%. The overall SFR in the UAS group and non-UAS group was 79% and 67%, respectively (P = 0.042). The SFRs were improved for calculi in all portions of the kidney.
• Conclusions: In addition to facilitating ureteroscopic access, reducing costs, and lowering intrarenal pressures, the results of the current study suggest that UASs improve SFRs during the management of renal calculi. It is now our current practice to use the UAS routinely during ureteroscopic treatment of renal and upper ureteral calculi.
  
  
• Editorial Comment
  Although the concept of the ureteral access sheath is not new, a recent redesign has resulted in a safer, more user-friendly and versatile product. A number of advantages have been demonstrated with use of the ureteral access sheath, including the ability to repeatedly access the upper tract and a reduction in intrarenal pressures. These benefits alone support the use of a ureteral access sheath in select cases. However, an advantage with regard to stone free rates has not been clinically demonstrated, despite the obvious benefit that stone fragments can be manually removed.
  In this retrospective study, L’Esperance and colleagues compared 256 cases of ureteroscopic management of renal calculi with or without a ureteral access sheath and determined that overall stone free rates were higher with (79%) than without (67%) the access sheath. When stratified by location in the collecting system, stone free rates were higher in all locations with the access sheath, although the differences did not reach statistical significance. Interestingly, despite higher stone free rates with use of the access sheath, no attempt was made to manually remove fragments after intracorporeal lithotripsy. Thus flow dynamics associated with the access sheath must encourage passage of fragments from the kidney. An obvious study of interest would be one in which every attempt is made to manually retrieve fragments from the kidney via the access sheath.
  This study suffers from the usual limitations of a retrospective series, in that selection bias with regard to patient selection may come into play and the fastidiousness with which the stone is treated could be affected by use of the access sheath. However, the results of this study are encouraging; now, a prospective randomized trial should be performed to confirm these findings. For now, use of a ureteral access sheath may be advantageous not only for lengthy and complex ureteroscopic cases, but perhaps for routine cases as well.

Dr. Margaret S. Pearle
Associate Professor of Urology
University of Texas Southwestern Med Ctr
Dallas, Texas, USA