Impact of Ureteral Stent Size on Stone-Free Rates in Ureteroscopic Lithotripsy for Ureteral Stones: Randomized Controlled Trial
Phornphen Prasanchaimontri MD*, Chaiyong Nualyong MD*, Tawatchai Taweemonkongsap MD*, Ekkarin Chotikawanich MD*
Affiliation : * Division of Urology, Department of Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
Objective : To determine the stone-free rates after ureteroscopic lithotripsy (URSL) between patients who had large and small
ureteral stent.
Material and Method: A prospectively randomized controlled study. Patients who underwent URSL between January 2014
and April 2015 were enrolled. Sixty eligible patients were randomized into 3 groups: non-stented as a control group (n = 20),
4.7 Fr stented (n = 20), and 6 Fr stented groups (n = 20). The lithotripsy technique was stone fragmentation using Holmium:
YAG laser (LumenismodelTM) until the fragment was smaller than 2 mm. The stone fragments were left in situ without
extraction. Primary outcome was stone-free rates detected by non-contrast-enhanced computed tomography (NCCT). Secondary
outcomes were irritative symptoms evaluated by overactive bladder symptoms score (OABSS), flank pain, hematuria,
urinary tract infection (UTI), auxiliary procedure, and readmission.
Results : The pre-operative characteristics of each group were similar. A stone-free rate in non-stented, 4.7 Fr stented, and
6 Fr stented groups was 95%, 85%, and 85% (p = 0.524), respectively. There was no statistically differences between 4.7 Fr
and 6 Fr stented groups for irritative symptoms (25% vs. 45%, p = 0.185), flank pain (10% vs. 5%, p = 0.548), asymptomatic
pyuria (35% vs. 25%, p = 0.288), febrile UTI (5% vs. 10%, p = 0.151) and hematuria (45% vs. 30%, p = 0.327). The
operative time, postoperative pain, analgesic requirement, length of hospital stay, auxiliary procedures, and readmission
were not different.
Conclusion : There was no difference in stone-free rates and stent-related adverse effects between small and large size
ureteral stent after URSL. The irritative symptoms and febrile UTI tended to be less in small stented.
Keywords : Ureteric calculi, Ureteroscopic lithotripsy, Ureteral stent, Stone-free rate
