STONE DISEASE

Prestenting improves ureteroscopic stone-free rates
Rubenstein RA, Zhao LC, Loeb S, Shore DM, Nadler RB
Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
J Endourol. 2007; 21: 1277-80

• Purpose: Although the use of stents after ureteroscopy has been studied extensively, relatively little has been published about stent placement before complicated ureteroscopic procedures. In this study, we examined our experience with stent placement before ureteroscopic management of renal and ureteral stone disease.
• Patients and Methods: A total of 90 patients underwent ureteroscopic surgery on 115 renal units by a single surgeon from 2001 to 2006. All patients had documented follow-up with imaging either by CT or intravenous urography (IVU) with tomography. Patients were classified into two groups depending on whether they had a stent placed before ureteroscopy. Baseline characteristics, operative indications for stent placement, stone-free rates, and complications were compared between groups.
• Results: Baseline characteristics were similar between the groups. The majority of patients received stents before stone management because of technical considerations during surgery (17/36, 47%) or infection (13/36, 37%). Strict stone-free rates after ureteroscopic treatment were 47% in the 79 procedures without previous stents, compared with 67% in the 36 procedures with prestenting (P < 0.05). Including small fragments (2 mm or smaller), stone-free rates improved to 54% v 78%, respectively (P < 0.02). Complications were not significantly different in the two groups (P = 0.70).
• Conclusion: Although routine stent placement is not necessary before all ureteroscopic procedures, we demonstrate that it is associated with good stone-free rates and few complications. In this retrospective cohort, prestenting was associated with significantly higher stone-free rates. Prestenting should be considered in challenging cases.
  
  
• Editorial Comment
  The authors state that when possible a larger and longer ureteral stent used for prestenting, however further details regarding the specific stent size are not provided. Similarly the authors do not comment on the duration of prestenting. The authors do not comment on their practice of fragmenting versus basketing the treated stone. The authors do not comment on the percentage of patients imaged with CT scan in each group – if a greater proportion of unstented patients underwent postoperative CT scan imaging, the higher sensitivity of the test may explain the noted differences in stone-free rates.
  Infection is known to result in decreased ureteral peristalsis, which theoretically could facilitate stone passage. Though 22% of the presented patients had calculi smaller than 5 mm, it is not reported what proportion of patients spontaneously passed stones prior to ureteroscopy. The authors utilized small ureteral access sheaths (10 mm internal diameter) in 20% of patients who were not prestented, and larger ureteral access sheaths (14 mm internal diameter) in 40% of patients who were prestented. One would anticipate that this would impact stone free rates, and may be the most important observation of this study. However, stone-free rates were not stratified based on sheath size. Similarly we are not told whether the decision to use a smaller sheath vs. larger sheath was empiric based on the presence of a stent or the result of difficulty passing a larger sheath.

Dr. Manoj Monga
Professor, Department of Urology
University of Minnesota
Edina, Minnesota, USA
E-mail: endourol@yahoo.com