Purpose: We aim to identify the prevalence and risk factors of three outcomes after stone removal following treatment for obstructive acute pyelonephritis (APN) associated with urinary tract calculi: immediate postoperative febrile urinary tract infection (UTI), stone recurrence, and APN recurrence during the follow-up period.
Materials and Methods: We retrospectively review the charts of 107 patients who underwent stone removal following treatment for obstructive APN associated with urinary tract calculi. Logistic regression analysis is used to identify the factors that contribute to postoperative febrile UTI after stone removal. Cox proportional hazard analyses are used to identify the factors contributing to stone recurrence and APN recurrence during the follow-up period.
Results: Postoperative febrile UTI was observed in 23 out of the 107 patients (21.5%). Multivariate logistic regression analysis revealed that female sex (P = .02) and having multiple stones (P < 0.01) were independently significant predictors of postoperative febrile UTI. One-year recurrence-free survival rates of stone disease and APN were 76.1% and 82.5%, respectively. Multivariable cox proportional hazard analyses revealed that residual fragments were the only significant risk factor for stone recurrence (P < 0.01) and marginally significant for APN recurrence (P = .05).
Conclusion: Patients presenting obstructive APN can develop postoperative febrile UTI after active stone removal with high frequency and the risk factors are female sex and having multiple stones. Residual fragments after stone removal in patients with obstructive APN can cause stone and APN recurrence, indicating that complete removal of stone fragments ? 4 mm is imperative to the management of the disease.