Anal Fistula & Abscess

Most often a blocked anal gland becomes infected by the normal bacteria of the bowel. Less commonly the cause is Crohn's disease, a previous injury or surgery, radiation, tuberculosis, or other infections. Diabetes and conditions that weaken the immune system can make the infection more serious. It is not caused by poor hygiene or by something you did wrong.

Anal abscesses are fairly common, especially in adults and more often in men. A fistula develops in a considerable share of people after an abscess. People with Crohn's disease are more likely to have fistulas, and these can be more complex.

Your doctor will look at and gently examine the area. An abscess is often recognised by the examination alone. To find the fistula tunnel and how it relates to the muscles that control the bowel (the sphincter), you may need an MRI of the pelvis, an ultrasound done through the anal canal, or an examination under anaesthesia by a colorectal surgeon. If Crohn's disease is suspected, a colonoscopy and other tests may be arranged. The doctor decides which tests you need.

An abscess is not something to treat at home. Simple measures help comfort and healing after a doctor has treated it.

• See a doctor promptly for any painful anal swelling; do not try to squeeze, pierce or cut it yourself

• Warm sitz baths (sitting in a few centimetres of warm water) can ease pain and keep the area clean after treatment

• Gently clean after bowel movements and pat dry; avoid harsh soaps and rubbing

• Use a pad or gauze if there is drainage, and change it when damp

• Follow wound-care and follow-up instructions, and tell the team if the pain or discharge returns

No special diet cures a fistula, but keeping stools soft avoids straining and pain.

• Eat fibre-rich foods such as vegetables, fruit, whole grains and legumes

• Drink enough fluids through the day

• Do not sit on the toilet for long periods or strain

• If you have diabetes, keep your sugar well controlled, as it helps healing

Medicines support treatment but do not replace drainage or surgery. Your doctor decides which, if any, you need.

• Simple pain relief as advised by your doctor

• Antibiotics only in selected situations, such as spreading infection, diabetes or a weak immune system

• Stool softeners or fibre supplements if constipation causes pain or straining

• For fistulas linked to Crohn's disease, specific bowel-disease medicines may be used by the specialist

Drainage of the abscess and, for a persistent fistula, a planned operation are the core of treatment.

• Incision and drainage of the abscess, often under local or general anaesthesia

• Fistulotomy (laying open the tunnel) for simple fistulas that do not involve much sphincter muscle

• A seton, a soft thread placed through the tunnel to keep it draining and prevent new abscesses

• Sphincter-sparing techniques such as flaps, plugs or glue for more complex fistulas

• Your surgeon will explain the risks, including recurrence and a small risk to bowel control

The main treatment of an abscess is drainage; antibiotics alone are not enough for most people, and are added only in selected situations. For fistulas, surgeons choose from several techniques that aim to close the tunnel while protecting the muscles that keep you continent. Treatment of fistulas in Crohn's disease often combines medicines with surgery.

After drainage, many people heal without further problems, but a fistula can remain or return, and it often needs a planned operation. Fistulas can usually be treated successfully, though some need more than one procedure. Surgery near the sphincter carries a small risk of changes in bowel control, which your surgeon will discuss with you.

• Do I have an abscess, a fistula, or both?

• Do I need an MRI or an examination under anaesthesia?

• Could this be related to Crohn's disease or another condition?

• Which operation do you recommend and what is the risk to my bowel control?

• How long will healing take and what care do I need at home?

This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the Approved for publication by SGA; individual clinician review is ongoing. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.