Is This Your Stone? Distinguishing Phleboliths and Nephroliths on Imaging in the Emergency Department Setting.

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Ureteral stones are a common diagnosis in the emergency department (ED) setting, often found with computed tomography (CT). The high frequency of phleboliths can confound ureteral stone diagnosis on CT imaging. This article provides a narrative review of the etiological, epidemiological, and radiological distinctions between ureteral stones and phleboliths for appropriate ED diagnosis and management. Multiple studies demonstrate phleboliths, benign calcified thrombi largely in pelvic vasculature, are found at frequencies equal to or greater than those of ureteral stones on CT imaging. The calcified foundation of phleboliths and most ureteral stones, as well as the close proximity of the distal ureters to pelvic vasculature, can cause consternation in the proper diagnosis of ureteral stones in the patient with abdominal pain. Radiological findings of circumferential ureteral soft tissue edema ("rim sign") and an irregular tapering soft tissue mass ("comet tail sign") can suggest a ureteral and phlebolith etiology, respectively. These signs demonstrate high specificity but low sensitivity, and clinicians must use history, examination, and secondary signs on imaging to differentiate ureteral stones from phleboliths. Phleboliths are a common finding on CT imaging. Radiological findings of rim sign and comet tail sign may help to differentiate phleboliths and ureteral stones; however, their low sensitivity and inconsistent presentation should prompt greater reliance on other signs of ureteral obstruction to aid in diagnosis of undifferentiated pelvic calcifications.