title: Image of the month. Congenital colonic duplication, sigmoid volvulus, Meckel's diverticulum, and emphysematous cystitis are considered in the differential diagnosis before surgery.
authors.affiliation: Montreal General Hospital, Quebec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Mehta
authors.forename: A N
authors.initials: AN
authors.lastname: Barkun
mesh_terms: D000368:Aged; D003106:Colon / Q000002:abnormalities; D003556:Cystitis / Q000175:diagnosis; D003937:Diagnosis, Differential; D004240:Diverticulum / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D004646:Emphysema / Q000175:diagnosis; D006801:Humans; D007415:Intestinal Obstruction / Q000175:diagnosis; D008297:Male; D008467:Meckel Diverticulum / Q000175:diagnosis; D011859:Radiography; D012810:Sigmoid Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery