What causes piles?
The lining of the back passage (anal canal) contains many blood vessels (veins). There seem to be certain changes in the veins within the lining of the back passage that cause the pile(s) to develop. The lining of the back passage and the veins become much larger and this can then cause a swelling and develop into a pile.
However, we don't know exactly what causes a pile. Some piles seem to develop for no apparent reason. It is thought that there is an increased pressure in and around the opening of the back passage (anus). This is probably a major factor in causing haemorrhoids in many cases. If you delay going to the toilet and need to strain when on the toilet then this can increase the pressure and so makes it more likely that a pile will develop.
About half of everyone in the UK develop one or more piles at some stage of their life.
What makes piles more likely?
There are certain situations that increase the chance of piles developing:
- Constipation, passing large stools (faeces), and straining at the toilet. These increase the pressure in and around the veins in the anus and seem to be a common reason for piles to develop.
- Being overweight. This increases your risk of developing piles.
- Pregnancy. Piles are common during pregnancy. This is probably due to pressure effects of the baby lying above the rectum and anus, and also the affect that the change in hormones during pregnancy can have on the veins. Piles occurring during pregnancy often go away after the birth of the child.
- Ageing. The tissues in the lining of the anus may become less supportive as we become older.
- Hereditary factors. Some people may inherit a weakness of the wall of the veins in the anal region.
- Other possible causes of piles include heavy lifting or a persistent (chronic) cough.
Did you find this information useful?
- Haemorrhoids; NICE CKS, July 2016 (UK access only)
- Haemorrhoidal artery ligation; NICE Interventional Procedure Guidance, May 2010
- Stapled haemorrhoidopexy for the treatment of haemorrhoids; NICE Technology Appraisal Guidance, September 2007
- Electrotherapy for the treatment of haemorrhoids; NICE Interventional Procedure Guidance, June 2015
- Hardy A, Cohen CR; The acute management of haemorrhoids. Ann R Coll Surg Engl. 2014 Oct 96(7):508-11. doi: 10.1308/003588414X13946184900967.
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