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.

Purpose: We 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 Methods: A 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.

Results: Spontaneous 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.

Conclusions: Stone 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.