Piles are caused by varicose veins in the anal canal.
Watts
G T
GT
D001003:Anal Canal / Q000098:blood supply*; D004032:Diet / Q000009:adverse effects; D006484:Hemorrhoids / Q000209:etiology*; D006801:Humans; D006975:Hypertension, Portal / Q000150:complications; D014648:Varicose Veins / Q000150:complications*