aetiology
Last reviewed 01/2018
The causes of haemorrhoids is not well understood but the following factors are important:
- constipation and prolonged straining at stool
- the typical Western diet is low in fibre and haemorrhoids are more common
- haemorrhoids are uncommon in developing countries
- increased anal sphincter tone:
- several effective treatments aim to reduce anal tone, including anal stretch procedures and nitroglycerine ointment
- obstruction of venous flow may play a role:
- during pregnancy
- in patients with portal hypertension