Materials and Methods
Patients with renal calculi detected on imaging, who underwent RIRS in the urology clinic of a tertiary hospital between January 2013 and May 2020, were included in the study. Preoperative and postoperative data of 681 patients were obtained from the hospital information system. During the preoperative period, all patients underwent physical examination, had their demographic data and medical history evaluated and underwent a hemoglobin along with analysis of serum urea, creatinine and white blood cell levels. Radiological imaging including kidney, ureter, and bladder (KUB) radiography, ultrasonography (USG) and abdominopelvic computed tomography (CT) was also performed.
Stone laterality (right-left), number (single and multiple), localization, stone density, stone size, presence of hydronephrosis, preoperative double-j (DJ) stent, congenital kidney anomaly and solitary kidney were evaluated preoperatively using imaging methods. Stone size was determined by measuring the longest axis on preoperative radiological examination. In cases with multiple stones, stone size was defined as the sum of the longest axis of each stone. Stone burden was defined as the two-dimensional area determined by multiplying the longest diameter by the perpendicular diameter of the stone. Infundibular length (IL) was measured as the distance from the farthest point below the calyx containing the stone to the midpoint of the lower edge of the renal pelvis. Infundibuloureteropelvic angle (IUPA) was measured as the internal angle formed at the intersection of the ureteropelvic axis and the central axis of the lower infundibular pole.
In RUSS, 4 parameters were evaluated for the patient with urinary system stone disease. For each parameter, 1 point was given to patients and the patients were scored with a score between 0-4. These parameters were the stone size > 20 mm, the IUPA < 45 degree for lower pole stones, stone number in different calyces and abnormal kidney anatomy such as horseshoe kidney or pelvic kidney.5The modified S-ReCS is scored according to the localization of the stone in the kidney.6 In R.I.R.S., all parameters are calculated using computed tomography images. In this system, the parameters of stone density (Houndsfield Unit (HU)), IUPA, IL, stone burden (mm) and precence of lower pole stone were checked.7 The patients were divided into two groups according to RUSS (0 points, 1-4 points), and three groups according to the modified S-ReCS score (low score: 1-2 points, medium score: 3-4 points, high score 5- 12 points) and four groups according to R.I.R.S. (low score: 4-5 points, medium score: 6-8 points, high score 9-10 points).
Preoperative urine cultures of all patients were sterilised. Prophylaxis with 2 g of cefazolin was administered intravenously to all patients within 1 hour before surgery. RIRS was performed in all patients under general anaesthesia in the lithotomy position. Ureterorenoscopy was performed with a 9.5 F rigid ureterorenoscope (Karl Storz, Tuttingen, Germany) before RIRS. In cases where ureteral dilatation was sufficient, after the access sheath reached the collecting system, the collecting system was reached by entering through the access channel with a 7.5 F flexible ureterorenoscope (Karl Storz, Flex X2, GmbH, Tuttlingen, Germany). In cases where the access sheath could not be delivered to the collecting system due to insufficient ureteral dilatation, a DJ stent was placed and RIRS was postponed for two weeks. The stone was fragmented using a holmium-yttrium-aluminum-garnet laser (200–365 μm) sent from the working channel of the flexible ureterorenoscope. The DJ stent and urethral catheter were used in all cases at the end of the operation. The patients were evaluated with KUB radioraphy, USG or CT in the postoperative first month. Success was defined as the absence of stones in the urinary system or the presence of asymptomatic residual stones ≤2 mm in size.
Infective complications after RIRS were defined as fever (body temperature >38°C continuing for 48 hours during hospital stay), urinary infection (urinary and/or blood culture positivity), sepsis (urinary infection) and presence of ≥2 Sequential Sepsis-related Organ Failure Assessment (SOFA) score and septic shock (sepsis accompanied by serum lactate level >2 mmol/L and vasopressor need for mean arterial pressure >65 mmHg).8