Material and Method:
After obtaining the approval of the local ethic committee and the informed consent from all patients in the study, we retrospectively analysed the medical records of all the patients who underwent FURS for renal stones larger than 20 mm in size between 2010 and 2019 in our tertiary academic centre. All operations were performed after appropriate antibiotic prophylaxis including second generation cefalosporine group and confirmation of no bacterial growth in preoperative urine culture. Patients who have concomitant ureter or bladder stones, presence of nephrostomy catheter during FURS, renal abnormality and operated under antibiotic suppression were excluded from the study.
Postoperative urinary infective complications such as fever, pyelonephritis and sepsis were investigated. The operated patients who had the body temperature lasting over 38 degrees for 48 hours or any body temperature over 39 °C was considered as infective fever after the exclusion of postoperative atelectasis. When the infection source established and the presence of two or more following Systemic inflammatory response syndrome (SIRS) criteria (body temperature < 36 °C or > 38 °C; heart rate > 90 beats/min; respiratory rate > 12/min or PaCO2 <32 mmHg; white blood cell count > 12,000 or < 4000/ mm3) determined in that case, it was accepted as sepsis.
The investigated parameters were age, body mass index (BMI), OT, size, surface area, density and location of the stones, usage of the UAS, the presence of the infection and stone free rates. The data were analyzed by forming two groups according to whether the OT was less than 60 minutes and more, whether the UAS was used and whether an infection occurred. In addition, independent risk factors that may affect postoperative urinary infection development were also investigated by logistic regression analysis. And, a ROC curve analysis was applied to determine a cut-off value in OT terms, where infection rates increase more.
Stone characteristics in terms of the size and density of all patients were evaluated with non-contrast abdominal computed tomography (CT) and the radio-opacity features of the stones were assessed with kidney-ureter-bladder (KUB) X-ray graphy, preoperatively. The longest/total longest diameter of stones was determined as stone size. Stone surface area was calculated using the formula: length x width x (π) x 0.25. Residual stones were evaluated with non-contrast abdominal CT or KUB radiogram in postoperative first month according to opacity of the stones. OT was defined as the time that passed between the beginning of the procedure when the device is inserted into the ureteral orifice and the moment of removing the FURS.