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

Abstract

Study Type – Diagnostic (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Although CT has become the gold standard for stone diagnosis, this study provides data suggesting that ultrasonography (US) is sufficient as primary diagnostic method for ureteral stones avoiding high costs, unnecessary radiation and long‐term risk of cancer. To our knowledge the identification of additional factors affecting diagnostic accuracy of US for ureteral stone diagnosis has not been established to date. 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.