Analysis of Factors' Association with Risk of Postoperative Urosepsis in Patients Undergoing Ureteroscopy for Treatment of Stone Disease

INTRODUCTION: To investigate which patient, stone, infective, and surgical factors were most likely to increase the risk of postoperative urosepsis within 28 days of ureteroscopy (URS) and laser stone fragmentation for ureteral or renal stones. METHODS: Data were collected prospectively in a single National Health Service institution. A logistic regression model was used to assess the association of factors with postoperative urosepsis. Two matched-pair analyses were used to assess the risk of postoperative urosepsis in patients with (a) an emergency presentation to hospital with urosepsis in the 90 days preceding URS and (b) a positive midstream sample of urine (MSSU) identified, but who were asymptomatic at preoperative assessment, who then received an appropriate course of antibiotics. RESULTS: Four hundred sixty-two consecutive patients were included in the study. Thirty-four patients (7.4%) had an episode of urosepsis within 28 days of their operation. A positive preoperative MSSU was significantly associated with postoperative urosepsis on multivariable analysis, despite appropriate treatment with a preoperative course of antibiotics: odds ratio (OR) 4.88, 95% confidence interval (CI) 2.11, 11.31, p < 0.001. The presence of diabetes mellitus, presence of ischemic heart disease, patient American Society of Anesthesiologists score, same-session bilateral URS, and stone volume were the other variables significantly associated with postoperative infection on univariable analysis, but these ceased to be significantly associated on multivariable analysis. Subgroup analysis found that a positive MSSU in both patients with a preoperative ureteral stent and those without was significantly associated with postoperative urosepsis, however, the OR was much lower for the stented group (OR 3.23 vs OR 16.67). On matched-pair analysis, patients with a positive preoperative MSSU were significantly more likely to have postoperative urosepsis compared to controls (OR 17.46, 95% CI 2.18, 139.80, p = 0.007). There was no significant difference in the OR of postoperative urosepsis in patients who had a preceding urine infection requiring hospital admission in the 90 days preceding URS (OR 0.60, 95% CI 0.19, 1.92, p = 0.39). CONCLUSIONS: Positive preoperative MSSU was significantly associated with postoperative urosepsis by logistic regression and matched-pair analysis. These higher risk patients should be counseled appropriately before surgery, and should be the focus of vigilant postoperative monitoring. The study suggests particular caution in patients with a positive preoperative MSSU without a preoperative ureteral stent.