Anal Lesion

An anal lesion could refer to haemorrhoids (piles) or an anal fistula (a small abnormality in the anal region).

Haemorrhoids - commonly known as piles - are swollen blood vessels (veins) which develop inside and/or outside the anus. If they become infected, they can cause pain and discomfort and may need treatment. When haemorrhoids do not respond to other treatments, or if they are large, or external, or they bulge, surgical removal by excision may be the best solution.

An anal fistula is a small channel that develops between the end of the bowel and the skin near the anus. It’s usually caused by an infection near the anus resulting in a collection of pus (abscess) in the nearby tissue. An anal fistula can also occur after surgery to drain an anal abscess.

The exact cause of haemorrhoids is not clear, but it is closely related to increased pressure in the blood vessels of your back passage. This can cause swelling and inflammation of these blood vessels.

An anal fistula can be caused by specific intestinal diseases such as Crohn’s disease. Around half of all anal fistulas develop when an infection around the anus results in an abscess. When the abscess discharges its pus a fistula can be formed. A previous, non-fully-healed abscess can also lead to a fistula being formed.

Your doctor can usually diagnose haemorrhoids and anal fistulas with a simple internal examination of your back passage, although they may need to refer you to a specialist for diagnosis and treatment.

Common symptoms of anal lesions (haemorrhoids and anal fistulas) include bleeding from your bottom after passing a stool, and itching and soreness around your anus.

  • Haemorrhoids are usually painless and often don’t cause any symptoms, so many people don't even realise they have them.
  • An anal fistula can be painful, as well as causing bleeding and discharge when passing stools. The main symptoms are pain and leakage of pus (sometimes blood-stained) from the fistula itself. This leakage will often relieve the pain. If an abscess is present, there will probably also be swelling around the anus.


  • bleeding (bright red blood) from the bottom after passing a stools
  • an itchy bottom
  • a red or sore anus
  • swelling around your anus
  • a lump hanging outside the anus after passing a stool
  • a mucus discharge from the anus after passing a stool

Anal fistula:

  • pain
  • bleeding and discharge when passing stools
  • swelling around the anus

Haemorrhoids (piles) often clear up by themselves, without intervention, after a few days. If your symptoms are more severe, you may need further haemorrhoid treatment such as banding (removing them by restricting their blood flow).

Anal fistulas very rarely heal by themselves and surgery is the only way to treat them.

Excision of anal lesion

The removal of a haemorrhoid or an anal fistula by cutting it out.

Excision of anal fistula

The surgical removal of an anal fistula

What next?

If you are suffering with a suspected condition, you should seek the advice of your doctor who will be able to refer you to Benenden Hospital for diagnosis and treatment.

There are four ways to access treatment at Benenden Hospital which include self-funding, using private medical insurance or your Benenden membership, or through the NHS e-Referral scheme.