In young adults with a low body mass index ultrasonography is sufficient as a diagnostic tool for ureteric stones

OBJECTIVE To identify additional factors that might improve the diagnosis of ureteric stones using ultrasonography (US) as the primary diagnostic method. PATIENTS AND METHODS We performed a retrospective study of 228 patients who underwent rigid ureterorenoscopy (URS) for obstructive ureteric stones. Patient age, sex, body mass index (BMI) and stone location and size were recorded. All patients underwent US for stone detection before surgery. If no cause of the flank pain was found by US, computer tomography (CT) was performed to confirm the absence of ureteric stones. RESULTS In 57 (25%), 15 (6.6%) and 156 (68.4%) patients a stone was localized on the proximal, mid- and distal ureter, respectively. In 96 (42.1%), 122 (53.5%) and 10 (4.4%) patients the stone measured 0-5, 6-10 and >10 mm, respectively. The mean (range) BMI of the patients was 24.7 (17.3-37.2) kg/m(2). The overall stone detection rate using US was 86.4% overall, and 96.4% in adults <= 35 years. In 72/197 patients (36.5%) the stones found using US measured <= 5 mm and in 24/31 patients (77.4%) the stones found using CT measured <= 5 mm. Age (P = 0.008), stone size (P < 0.001) and BMI (P = 0.013) were factors that independently affected ureteric stone diagnosis using US. CONCLUSION Although CT has served as the 'gold standard' for stone detection, its high costs and radiation dose, together with the high detection rate of US in the hands of experienced radiologists, lead us to conclude that US should be the first choice for primary diagnostic purposes, especially in young slim adults as no patient <= 35 years with a BMI <= 24 kg/m(2) needed unenhanced CT for ureteric stone diagnosis.