Upper gastrointestinal endoscopy--is it a first-line diagnostic service?
D004724:Endoscopy / Q000592:standards*; D004935:Esophageal Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005767:Gastrointestinal Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D011859:Radiography