Predictors for spontaneous stone passage in patients with renal colic secondary to ureteral calculi.

OBJECTIVES

To determine the clinical, laboratory, and imaging variables that can predict spontaneous stone passage in patients with renal colic secondary to ureteral calculi.

METHODS

We prospectively analyzed the medical records of 114 patients who admitted to the emergency department for renal colic from June until November of 2010. Forty-six of them were excluded. The presence of ureteral calculi was confirmed by either a kidney-ureter-bladder plain film or an ultrasound or a computer tomography. In all patients, a second visit after 1 month was planned and the stone status was checked by the same imaging techniques.

RESULTS

From the 68 patients, 16 had a calculus in the upper ureter, 10 in the mid ureter, and 42 in lower part. Stone size was ranged from 2.3 to 15 mm, 52.9% of them were located in the left ureter and 51.5% were radiopaque. Stones passed spontaneously in 36 patients. In multivariate analysis, serum white blood cell count found to be the most significant predictor (P = 0.028) for spontaneous passage followed by stone size (P = 0.037). In analysis of patients with stone size <10 mm, left side (P = 0.017) and serum white blood cell count (P= 0.032) found to be significant predictors.

CONCLUSIONS

Serum white blood cell count is an easy to assay variable in everyday practice. This study showed that its value, at the acute phase of a renal colic, is a significant predictor for stone spontaneous passage and should be considered. Stone size remains a valuable predictor. Stones <10 mm on the left ureter have a higher likelihood to pass spontaneously.