title: [What is the cause?].
authors.forename: Peter
authors.initials: P
authors.lastname: Stiefelhagen
mesh_terms: D003937:Diagnosis, Differential; D006471:Gastrointestinal Hemorrhage / Q000209:etiology*; D006801:Humans; D011349:Proctitis / Q000209:etiology*; D012002:Rectal Diseases / Q000175:diagnosis*; D012007:Rectum