PURPOSE: Although retrograde intrarenal surgery (RIRS) is a minimally invasive treatment, postoperative urinary tract infection develops between 9% and 25%. The aim of this study was to investigate the factors predicting postoperative early infection after RIRS. MATERIAL-METHODS: Of the 642 patients who underwent RIRS for proximal ureteral stone and / or kidney stone between September 2013 and July 2019, 289 patients with a total stone size of 1-2 cm were included in the study. Patients were divided into two groups with and without postoperative urinary tract infection. The demographic data and perioperative findings of all patients were retrospectively reviewed. Sterile urine cultures were obtained in all patients during the preoperative 30-day period and urine analysis values were included in the data. RESULTS: Urinary system infection (UTI) was seen in 20 (6.9%) of 289 patients who had RIRS with 1-2 cm stones. The majority of the patients who developed postoperative UTI were female, whereas the rate of male patients was higher in the non-UTI patients (55% vs 39.8%, p = 0.181). Age, body mass index, accompanying diabetes mellitus, hypertension, Charlson comorbidity index were similar. There was no statistically significant difference between the two groups in terms of stone diameter and stone localization (median diameter 13.5 vs 15, p = 0.285). Patients with postoperative UTI had a higher rate of UTI history (55% vs 20.5%, p = 0.000) and longer operative times (62.5 ± 16.6 vs 60 ± 19.4, p = 0.008) (Table-1). It was found that in patients with postoperative UTI, leukocyte was higher in urinanalysis, which was obtained at the same time with sterile uriner cultures. Rate of pyuria, leukocyte esterase and nitrite positivity were observed more frequently in patients with postoperative UTI (Table-2). In multivariate analysis; UTI history, prolonged operative time, and nitrite positivity in preoperative urinanalysis were found to be independent risk factors for postoperative UTI in RIRS patients with stones between 1-2 cm (Table-3).

CONCLUSION: Nitrite positivity in preoperative urinanalysis, history of UTI and prolonged operation time are the factors that predict the postoperative infection in RIRS for stones between 1-2 cm. With those patients, clinicians should be careful for febrile UTI in the postoperative period.