title: Classification of perianal Crohn's disease.
mesh_terms: D001004:Anus Diseases / Q000145:classification* / Q000175:diagnosis; D003424:Crohn Disease / Q000145:classification* / Q000150:complications / Q000175:diagnosis; D003937:Diagnosis, Differential; D006801:Humans; D012003:Rectal Fistula / Q000209:etiology