Methods
After obtaining the approval of the ethics committee (01/04/2021.05-25), the data of 129 patients who underwent f-URS on renal and proximal ureteral stones in two centers between 2015 and 2020 were prospectively recorded in a database and retrospectively analyzed. All the patients were evaluated preoperatively using 64-detector non-contrast computed tomography (NCCT). The renal pelvis Hounsfield units (HU) of the patients with hydronephrosis were measured and recorded using the technique described by Basmacı et al. [14]. Wall thickness at the location of the stones in the proximal ureter and pelvis was measured and recorded as defined by Sarica et al. [15]. Stone parameters evaluated consisted of number, size (measured as the longest diameter of the stone in NCCT in axial or reconstructed coronal planes), and CT attenuation value. Patient data obtained included age, gender, body mass index (BMI), history, physical examination findings, and specific comorbidities.
PBUC and RPUC were performed using 5% sheep blood agar and eosin-methylene blue agar and incubated at 37 °C for 18-24 h. The results were quantitatively evaluated [16,17]. The bacterial growth of ≥ 10 5cfu/ml was determined as positive.
PBUC was taken from all the patients preoperatively, and if negative, intravenous cefazolin was administered as PAP with the induction of anesthesia according to the EAU guidelines [9]. In case of a positive PBUC before f-URS, the operation was not performed until a negative PBUC was achieved with appropriate antibiotherapy. Patients with a previous history of urological operation, urinary system catheterization or congenital urinary system anomalies, cases in which a double-J stent was placed for passive dilation at the time of the first operation and the operation was delayed, steroid users, and pregnant women were not included in the study.
All operations were performed with the patients in the lithotomy position under general anesthesia. First, ureteroscopy was performed with a semirigid ureteroscope (8 Fr; Karl Storz, Tuttlingen, Germany) to provide active dilatation and place a guidewire. At this stage, approximately 10 cc of available urine sample was taken from the renal pelvis for the RPUC analysis. Then, according to the surgeon’s preference, a ureteral access sheath (UAS) (Flexor 9.5/11.5Fr or 12/14Fr, Cook Medical Bloomington, IL, USA, Navigator 11/13Fr, Boston Scientific, Natik, MA, USA) was placed under fluoroscopic inspection over the guidewire. If UAS could not be placed, the operation was performed without a sheath. In all patients, f-URS was performed using flexible ureteroscopes (Flex-X2, Karl Storz Endoscope, Tuttligen, Germany) and a 200/273 micron Holmium laser lithotriptor. The procedure was terminated after stone-free status was confirmed by both ureteroscopic inspection and fluoroscopy (leaving only ungraspable gravel or fragments <2mm), in cases of bleeding, or if deemed necessary by the surgeon. At the end of the operation, a double-J stent or a ureteral catheter was placed according to the surgeon’s preference. On the first postoperative day, the patients were discharged if there was no hematuria or fever.