What about a vicious circle causing and perpetuating various benign anal diseases?
D000038:Abscess / Q000209:etiology / Q000601:surgery; D001003:Anal Canal / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery; D000768:Anesthesia, General; D000772:Anesthesia, Local; D001004:Anus Diseases / Q000601:surgery*; D003248:Constipation / Q000150:complications; D003672:Defecation / Q000187:drug effects; D004106:Dilatation; D005242:Fecal Incontinence / Q000209:etiology; D005401:Fissure in Ano / Q000209:etiology / Q000601:surgery; D006801:Humans; D009132:Muscles / Q000601:surgery; D009892:Opium / Q000627:therapeutic use; D011183:Postoperative Complications; D012005:Rectal Prolapse / Q000209:etiology / Q000601:surgery
D009892:Opium