Predicting Factors for Spontaneous Passage of Ureteral Calculi Based on Unenhanced Helical CT Findings

Song, Dong Woo; Jeong, Tae Yung; Lee, Sang Ik; Kim, Dong Jun

Abstract

PURPOSE: We performed a prospective study to determine whether unenhanced helical computed tomography(UHCT) findings predict the spontaneous passage of ureteral calculi.
MATERIALS AND METHODS
Between April 2006 and June 2007, 175 patients with a single ureteral calculus <1cm in diameter were enrolled in this study, and a UHCT was performed. All of the patients were managed conservatively for 2 weeks. Patients without spontaneous passage of ureteral calculi within 2 weeks were treated by ureteroscopy or extracorporeal shock wave lithotripsy(ESWL). The secondary signs (hydronephrosis, perinephric edema, and the tissue rim sign) were graded on a scale of 0-3. We evaluated whether spontaneous passage of ureteral calculi was associated with stone diameter, location, Hounsfield units(HU), and the degree of secondary signs.
RESULTS
Ninety-two patients(52.6%) had spontaneous passage of ureteral calculi. The mean stone diameter was significantly smaller in the passage group than the non-passage group(4.28mm vs. 6.73mm, p=0.002). The rate of spontaneous passage was significantly higher involving distal ureteral calculi(66.1%) than proximal ureteral calculi(30.3%, p<0.001). The incidences of hydronephrosis and perinephric edema were significantly lower in the spontaneous passage group than the non-passage group(8.7% vs. 73.5% and 5.4% vs. 69.9%, respectively). The grades of hydronephrosis and perinephric edema were significantly lower in the spontaneous passage group than the non-passage group(p=0.001). Although there was a tendency toward increasing grades of hydronephrosis and perinephric edema with increasing stone size, the grades were more frequent and severe in the non-passage group in patients with similarly sized stones.
CONCLUSIONS
The degree of hydronephrosis and perinephric edema are useful ancillary signs in predicting the likelihood of spontaneous passage of ureteral calculi.