Postoperative febrile-urinary tract infections (f-UTI) are one of common complications following flexible ureteroscopy (f-URS). The incidence of infectious complications is higher in patients with preoperatively positive urine cultures (PUC). Excessive intrarenal pressure (IRP) during f-URS is one of risk factors related to postoperative complications due to bacteria absorption, so intraoperative control of IRP may be critical issue to prevent them. In this study, we prospectively investigate whether IRP monitoring during f-URS with LithoVue Elite (LVE) could contribute to reduce the incidence of postoperative f-UTI in patients with preoperatively PUC.

A total of 104 patients underwent f-URS in 5 hospitals for upper tract urinary calculi were enrolled in this study. The eligibility criteria were as follows; patients whose age were more than 20 years old, and who had PUC preoperatively. The exclusion criteria were as follows; patients with active febrile urinary tract infection, with a nephrostomy and women with pregnant or its possibility. The surgeons regulated less than 30mmHg IRP under real time monitering during whole process of f-URS as much as possible they can. The primary outcome was set for incidence of postoperative f-UTI until discharge.

The incidence of postoperative fever was 7.7 % (n=8). In f-UTI patients, operation time was 62.1±21.0 min, mean IRP was 17.1±11.3 mmHg, and time over 30mmHg was 6.9±9.4 min. on the other hand, in non f-UTI patients, operation time was 57.3±26.1 min, mean IRP was 12.5±17.3 mmHg, and time over 30mmHg was 5.9±9.4 min. However, in terms of IRP factors, there were no significant differences between f-UTI and non f-UTI groups.

This was a first IRP study for clinical patients with PUC. We found that one of new thresholds might present around 17.3mmHg in fURS to prevent postoperative f-UTI. Real time monitoring of IRP may contribute to reduce the risk of postoperative fever following fURS.