• K Xafis, G Thalmann, L M Benneker, C Stoupis, D J Buggy, H Zimmermann, and A K Exadaktylos.
• Department of Emergency Medicine, University Hospital of Berne, Berne 3010, Switzerland.
• Emerg Med J. 2008 Oct 1; 25 (10): 640-4.

BackgroundAlthough urinalysis is simple and inexpensive to perform, the finding of microhaematuria on urinalysis may be unreliable for diagnosing urolithiasis.ObjectiveTo evaluate microhaematuria as a diagnostic marker for urolithiasis compared with low-dose unenhanced multidetector computed tomography (MDCT) as the "gold standard".SettingA level 1 emergency department in a tertiary referral university teaching hospital.DesignRetrospective analysis.MethodsA study was undertaken to assess whether the finding of microhaematuria was diagnostic for urolithiasis using a low-dose unenhanced MDCT-based diagnosis as the reference standard by reviewing the records of all patients who presented to the emergency department with colicky flank pain and underwent a CT scan between January 2003 and December 2005.ResultsUrolithiasis was present (as defined by low-dose unenhanced MDCT) in 507/638 patients (79%); 341/638 (53%) were true positive for urolithiasis, 76 (12%) were true negative, 55 (9%) were false positive and 166 (26%) were false negative. Microhaematuria as a test for urolithiasis in patients presenting to the emergency department therefore has a sensitivity, specificity, positive predictive value and negative predictive value of 67%, 58%, 86% and 31%, respectively. 58% of the urinalysis results were negative for haematuria in the subset of patients with significant alternative diagnoses.ConclusionsThe sensitivity, specificity and negative predictive value of microhaematuria on urinalysis for urolithiasis using unenhanced MDCT as the reference standard were low. This suggests that, when urolithiasis is clinically suspected, unenhanced MDCT is indicated without urinalysis being a prerequisite.

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