The exact cause of piles isn’t known. One theory is that it’s due to weakness of the tissue that connects the anal cushions to the muscle layers underneath. Due to this weakness, the anal cushions slide out of their normal place and down the back passage.
You have an increased risk of getting piles if you:
- strain to empty your bowels (eg if you have constipation)
- eat a low-fibre diet
- have long-lasting (chronic) diarrhoea
- are pregnant – due to the effect of hormones on the blood vessels, plus the increasing weight of the baby within your abdomen
- have a family history of piles
- have cancer or growths in your pelvis or bowel, which may put increased pressure on your abdomen