Editorial comment

Abstract

Noncontrast enhanced helical CT scanning will detect urinary tract stones in roughly 95% to 98% of patients who have them. 1 Fielding J.R. Steele G. Fox L.A. et al. Spiral computerized tomography in the evaluation of acute flank pain a replacement for excretory urography. J Urol. 1997; 157: 2071-2073 Abstract Full Text Full Text PDF PubMed Scopus (215) Google Scholar , 2 Dalrymple N.C. Verga M. Anderson K.R. et al. The value of unenhanced helical computerized tomography in the management of acute flank pain. J Urol. 1998; 159: 735-740 Abstract Full Text Full Text PDF PubMed Scopus (297) Google Scholar Making an accurate diagnosis in the remaining 2% to 5% of patients with undetected urinary tract stones represents a diagnostic challenge. In these uncommon cases, urologists and radiologists must rely on “secondary” signs of ureteral obstruction. Historically, these signs have included hydronephrosis, hydroureter, unilateral renal enlargement, perinephric stranding, periureteral stranding, and the ureteral tissue rim sign. Of these signs, however, only hydronephrosis and hydroureter occur with relative frequency (70% to 90% of cases) and, hence, have a reasonably high sensitivity. 3 Ege G. Akman H. Kuzucu K. et al. Acute ureterolithiasis incidence of secondary signs on unenhanced helical CT and influence on patient management. Clin Radiol. 2003; 58: 990-994 Crossref PubMed Scopus (55) Google Scholar The other signs occur with less frequency and are, therefore, only helpful if they are present (high specificity but low sensitivity).