Preoperative urine culture with contaminants is not associated with increased risk for urinary tract infection after ureteroscopic stone treatment.

Purpose: We aimed to assess whether the presence of contaminants in the pre-operative urine culture (preop-UC) predicts postoperative urinary tract infection (postop-UTI) in patients undergoing elective ureteroscopy with laser lithotripsy.

Methods: A retrospective chart review was performed from 01/2019 to 12/2021 examining patients with unilateral stone burden ≤ 2 cm who underwent ureteroscopy with laser lithotripsy and had a preop-UC within 3 months. Positive, negative, contaminated, and polymicrobial definitions for UCs were established in accordance with current guidelines. Patients with positive and polymicrobial cultures were excluded. Postop-UTI was defined as the presence of urinary symptoms and a positive UC within 30 days of the procedure. Multivariable logistic regression models were utilized to evaluate risk factors for contamination in the preop-UC and the risk of postop-UTI.

Results: A total of 201 patients met the inclusion-exclusion criteria. Preop-UC was negative in 153 patients and contaminated in 48 patients. Significant contaminant-related factors included female gender and increased BMI. Postop-UTI was diagnosed in 3.2% of patients with negative preop-UCs and 4.2% of patients with contaminants, with no difference between groups (p = 0.67). The regression model determined that the presence of contaminants in preop-UC failed to predict postop-UTI (OR 0.69, p = 0.64).

Conclusion: The presence of contaminants in preop-UCs is not associated with an increased risk of postop-UTIs after ureteroscopy. Our study supports that contaminants in the preop-UC can be interpreted as a negative UC in terms of postop-UTI risk stratification. Preoperative antibiotics should not be prescribed for patients undergoing uncomplicated ureteroscopy for stone surgery in the setting of a contaminated preop-UC.