title: The missing balloon sign.
abstract: The balloon of the self-retaining Foley catheter should be readily visible during ultrasound scanning of the distended urinary bladder. Its absence should prompt a search for its location since extra-vesical inflation may result in local trauma and confusing appearances.
mesh_terms: D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D014463:Ultrasonography; D014546:Urinary Catheterization / Q000009:adverse effects*; D014570:Urologic Diseases / Q000209:etiology