Predictive Factors for Spontaneous Stone Passage and the Potential Role of Serum C-Reactive Protein in Patients with 4 to 10 mm Distal Ureteral Stones: A Prospective Clinical Study

PurposeWe investigated possible predictive factors for spontaneous stone passage and the potential role of serum C-reactive protein and white blood count in patients with 4 to 10 mm distal ureteral stones.Materials and MethodsA total of 251 patients who presented with renal colic secondary to distal ureteral stone were included in study. Patients were grouped according to spontaneous stone passage. Serum C-reactive protein, white blood count and other possible factors were investigated for their potential predictive value for spontaneous stone passage at a followup of 5 weeks. Potential predictive factors for spontaneous stone passage were evaluated with univariate and multivariate analyses. ROC curve analysis was performed to find an optimal cutoff value for serum C-reactive protein according to spontaneous stone passage. Statistical significance was considered at p <0.05.ResultsSpontaneous stone passage was observed in 135 patients (53.8%) in group 1 while 116 (46.2%) in group 2 did not expel the stone spontaneously. Median stone size was 5.7 mm. Stone size, serum C-reactive protein and white blood count were significantly higher in group 2 than in group 1. The number of patients with hydronephrosis and the number with spontaneous stone passage history were significantly lower in group 2 compared to group 1. The cutoff value of serum C-reactive protein provided by ROC analysis was 0.506 mg/l. Time to spontaneous stone passage was significantly higher in patients with serum C-reactive protein above the threshold and in patients with ureteral stones greater than 6 mm.ConclusionsStone size, previous spontaneous passage, hydronephrosis, serum C-reactive protein and white blood count can be used to predict spontaneous stone passage in patients with 4 to 10 mm distal ureteral stones. A serum C-reactive protein level of 0.506 mg/l can serve as a cutoff value to predict spontaneous stone passage.