Association of Severe Microscopic Hematuria with Successful Conservative Treatment of Single Uncomplicated Ureteral Calculus: A Multicenter Cohort Study

Background: Although detection of microscopic hematuria is a well-known diagnostic method for urolithiasis, its ability to predict urolithiasis treatment outcomes in adults is unknown. Objective: To evaluate the role of microscopic hematuria in conservative treatment of ureteral calculus. Design, setting, and participants: This cohort study involved 482 patients who were diagnosed with a single uncomplicated ureteral calculus (≤10 mm) using computed tomography and underwent conservative therapy at two Japanese community hospitals between 2013 and 2018. Patients were divided into three groups according to the severity of microscopic hematuria (no, ≤4; mild to moderate, 5–99; and severe, ≥100 red blood cells per high-power field) and as determined during the first emergency department or urologic outpatient clinic visit. Outcome measurements and statistical analysis: A multivariate logistic regression analysis was performed to estimate the odds ratio for successful conservative therapy at 28 d after the diagnosis. Statistical significance was set at p < 0.05. Results and limitations: Of the 482 patients, 81 (16.8%), 209 (43.4%), and 192 (39.8%) had no, mild to moderate, and severe microscopic hematuria, respectively. After adjustments for six relevant confounders, severe microscopic hematuria showed a significant association with successful conservative therapy at 28 d (adjusted odds ratio, 1.91; 95% confidence interval, 1.02–3.57; p = 0.043), whereas mild to moderate microscopic hematuria did not (adjusted odds ratio, 1.05; 95% confidence interval, 0.57–1.93; p = 0.872) when compared with no microscopic hematuria. Conclusions: Severe microscopic hematuria was significantly associated with successful conservative therapy for single uncomplicated ureteral calculus. Patient summary: Microscopic hematuria might have predictive value for conservative treatment of a single uncomplicated ureteral calculus. Using the presence or absence of blood in urine and other predictive factors, clinicians may lead patients with a single uncomplicated ureteral calculus to successful conservative therapy. Microscopic hematuria might have predictive value for conservative treatment of a single uncomplicated ureteral calculus, in addition to its diagnostic value. Of note, severe microscopic hematuria, defined as 100 red blood cells high power field, might provide useful information when considering conservative therapy.