Which Objective Parameters Are Associated with a Positive Urine Culture in the Setting of Ureteral Calculi: The Ureteral Calculi Urinary Culture Calculator.

OBJECTIVE: To determine associations between laboratory values and subsequent culture positivity in the acute ureteral calculi patient. Specifically, we aim to develop a predictive model to assist with optimization of patient outcomes and improvement of antimicrobial stewardship.

METHODS: Utilizing the electronic medical record system, we conducted a retrospective review of 3888 patients with ureteral calculi. Relevant demographic information, vital signs, and laboratory parameters obtained in the emergency department were tabulated. We applied a combination of analysis of variance and Pearson Fisher's Exact test for the analysis.

RESULTS: A total of 3888 patients were included in the analysis of whom 3171 (81.6%) had a negative urine culture and 717 (18.4%) had a positive urine culture. Basic vital signs and laboratory parameters, such as heart rate, temperature, white blood cell (WBC) count, platelet count, and neutrophil differential only varied slightly in the positive and negative culture groups. Urinary nitrite was found to have specificity of 97.2% with a negative predictive value of 83.7%. Urinary leukocyte esterase was found to have a sensitivity of 86.8% and positive predictive value of 46.9%. On microscopy analysis, WBCs per high power field (WBCs/hpf) varied directly with likelihood of a positive urine culture; >150 WBCs/hpf had an 86.1% likelihood of positive urine culture.

CONCLUSION: With the data provided from this large cohort analysis, we were able to create the ureteral calculi urinary culture calculator. With this calculator, urologists are better equipped to stratify a patient's risk of having a positive urine culture in the setting of a ureteral calculus.