Can ureteral stones cause pain without causing hydronephrosis?

Abstract

While computerized tomography (CT) is the gold standard for diagnosis of ureterolithiasis, ultrasound is a less costly and radiation-free alternative which is commonly used to evaluate patients with ureteral colic. The purpose of this study was to evaluate the frequency with which patients with ureteral stones and renal colic demonstrate hydronephrosis in order to better understand the evaluation of these patients. Two hundred and forty-eight consecutive patients presenting with ureteral colic and diagnosed with a single unilateral ureteral stone on CT scan in an urban tertiary care emergency department were retrospectively reviewed. Radiology reports were reviewed for stone size, diagnosis, and degree of hydronephrosis. Of the 248 patients evaluated for suspected ureteral stone, 221 (89.1%) demonstrated any hydronephrosis, while 27 (10.9%) did not. Hydronephrosis grade, available in 194 patients, was as follows: mild-70.6%, moderate-27.8%, and severe-1.5%. Mean patient age was 47.0years (SD 15.5), gender distribution was 35.9% female and 64.1% male, and mean stone axial diameter was 4.1mm (SD 2.4). Stone location was as follows: ureteropelvic junction-4.1%, proximal ureter-21%, distal ureter-24.9%, and ureterovesical junction-47.1%. Axial stone diameter and coronal length (craniocaudal) were both significant predictors of degree of hydronephrosis (ANOVA, p<0.001 for both). Age (ANOVA, p=NS), stone location (Chi square, p=NS), and gender (Chi square, p=NS) were not associated with degree of hydronephrosis. In patients with ureteral stones and colic, nearly 11% do not demonstrate any hydronephrosis and a majority (nearly 71%) will demonstrate only mild hydronephrosis. Stone diameter appears to be related to degree of hydronephrosis, whereas age, gender, and stone location are not. The lower incidence of hydronephrosis for small stones causing renal colic may explain the lower diagnostic accuracy of ultrasound when compared to CT for detecting ureteral stones.