Materials and Methods
We performed a retrospective analysis of 949 patients who were underwent f-URS and laser lithotripsy for renal stones in two institutions (HSU Izmir Bozyaka Training and Research Hospital, HSU Ankara Diskapi Training and Research Hospital) between March 2015 and June 2020. Preoperative evaluation of the patients included medical history, physical examination, complete blood count, urine analysis and culture, serum biochemistry and non-contrast computed tomography (NCCT). All patients were given antibiotic prophylaxis according to current guidelines. Stone characteristics and renal anatomical characteristics were evaluated on NCCT. Stone size was determined by measuring the longest axis at NCCT; in case of multiple stones the sum of each stone size was calculated. Stone surface area and lower pole infindibulo-pelvic angle (IPA) was measured as defined before [6,7]. All procedures were performed by experienced surgeons by using different size and brand ureterorenoscopes (7.5F Flex –X2™ (Karl Storz,Tuttlingen Germany), Olympus URF P-5™ (Olympus, Tokyo, Japan), 9.5F Pusen™ (Zhuhai Pusen Medical Technology Co, Ltd., Zhuhai, China). Patients with missing data and/or lacking of 1st month post-operative NCCT were excluded from the study. All procedures were performed under general anesthesia in lithotomy position. A diagnostic ureteroscopy with a semi-rigid ureterorenoscope was always performed at the beginning of surgery both to dilate the ureter and pass a safety guidewire. A ureteral access sheath (9,5-11,5; 12-14 Fr) was placed according to surgeon’s preferences. The stones were fragmented by using a holmium: YAG laser. If needed some fragments were removed with tipless nitinol stone baskets. At the end of procedure, a D-J stent was placed according to surgeon’s decision. All patients were evaluated with NCCT at 1st month for stone-free status. Residual fragments <2mm were accepted as insignificant.
The RUSS, modified S-ReSC, Ito’s nomogram and R.I.R.S. scores were calculated for each patient by same surgeon on imaging methods. Results were compared for their predictive capability of stone-free status and complications.