MODEL RELEASED. Prolapsed piles and rectal mucosa in a 92-year-old woman. Piles, also known as haemorrhoids, are swollen veins that protrude from the anus. The anus is the external opening of the rectum, the final part of the digestive tract from which faeces are expelled. Straining to expel hard faeces, places pressure on the veins in the lining of the rectum, causing them to swell. They can rupture and bleed during defecation, and cause pain. A lack of fibre and water in the diet makes haemorrhoids more likely. Ointments can reduce the swelling, but severe cases, which can include prolapse (external extrusion) of the rectum and its mucosal lining, require surgery.