14466 Anal Fistula

Overview

An anal fistula is a small tunnel that develops between the end of the bowel (the anus) and the skin near the anus. It usually happens after an infection in a gland inside the anus creates an abscess (a pocket of pus). The tunnel is the leftover drain for that infection.

Anal fistulas are not very common, but they are not rare either. Around 1 in 10,000 people develop one each year.

Anal fistulas can affect people of any age, but they are most common in men between 30 and 50 years old. People with inflammatory bowel disease (such as Crohn's disease) are more likely to develop one.

Symptoms

Common symptoms

• Throbbing pain around the anus, which can be worse when sitting, passing stool, or coughing.
• Swelling and redness around the anus.
• Discharge of pus, blood, or fluid from a small opening near the anus.
• Irritation and itching around the anus.
• A feeling of being generally unwell, sometimes with a low fever.

Symptoms in children

• Babies and young children may be fussy, cry during nappy changes, or show discomfort when passing stool.
• There may be a small lump or a draining sore near the anus.
• You may notice blood or pus on the nappy or toilet paper.

Symptoms in older adults

• Symptoms may be less obvious and can be mistaken for hemorrhoids.
• An older adult might experience discomfort in the anal area, constipation, or a sense that something is not right.
• If an infection spreads, they may become confused or very weak, which is a medical emergency.

Causes

Main causes

• An infection in an anal gland that becomes an abscess and then leaves a tunnel behind.
• Inflammatory bowel disease, such as Crohn's disease or ulcerative colitis.
• Injury to the anal area, surgery, or previous radiation therapy in the pelvic region.

Risk factors

• Having a previous anal abscess.
• Having Crohn's disease or ulcerative colitis.
• Having a weakened immune system (from illness, medicines, or certain treatments).
• Being male and between 30 and 50 years old.

When to see a doctor

See a doctor urgently if:

• If you have severe pain around your anus with a fever or chills.
• If you have a painful lump in the anal area that is growing or weeping fluid.
• If you have diabetes or a weakened immune system and notice any anal pain, swelling, or discharge.

Book a routine appointment if:

• If you have ongoing pain, swelling, or discharge around the anus that does not go away after a few days.
• If you notice blood or pus in your stool or on toilet paper.
• If you have changes in bowel habits or discomfort that keeps coming back.

Diagnosis

Your doctor will ask about your symptoms and examine the area around your anus. They may also look inside your anal canal. Sometimes the opening of the fistula is visible, and the doctor may gently press on it to check for discharge.

Tests that may be done

• Physical examination of the anal and perianal area.
• MRI (magnetic resonance imaging) scan, which gives a detailed picture of the fistula.
• Ultrasound, sometimes used to see the fistula tract.
• A fistulogram, where a dye is injected into the opening and X-rays are taken.
• Sigmoidoscopy, a test where a thin, flexible camera looks at the lower part of the bowel.

What to expect at your appointment

A doctor will discuss the findings with you and explain any tests clearly. You may be referred to a specialist, such as a colorectal surgeon, for further evaluation. The process is generally not painful, though you may feel some discomfort during the examination.

Treatment

The main treatment for an anal fistula is surgery. The type of surgery depends on where the fistula is, how deep or complex it is, and your overall health. Medicine alone rarely cures a fistula, but pain relief and antibiotics may be used if needed.

Self-care at home

• Keep the area clean and dry; gently wash with warm water after bowel movements.
• Take warm baths (sitz baths) several times a day to help soothe pain and keep the area clean.
• Wear cotton underwear and change dressings or pads as needed to soak up any discharge.
• Avoid sitting for long periods, and use a soft cushion if sitting is uncomfortable.
• Do not strain during bowel movements; keep your stools soft by drinking enough water and eating fiber-rich foods.

Medical treatments

Medical care for an anal fistula can include pain relief (advised by your doctor or pharmacist) and possibly antibiotics if there is an active infection. Some fistulas may be managed with a temporary drainage seton — a soft thread placed in the tract to keep it open and allow infection to drain. Your healthcare team will recommend the most appropriate approach for your situation.

When is surgery considered?

Surgery is usually needed to close the fistula and prevent it from coming back. There are several surgical options, from a simple fistulotomy (opening the tract) to more complex procedures that spare the sphincter muscles. A colorectal surgeon will discuss the best option with you.

Living with this condition

Living with an anal fistula requires regular hygiene and managing any discharge. You may need to use pads or dressings. Pain is usually manageable with warmth, rest, and simple pain relief. After treatment, most people return to normal activities within a few weeks.

Lifestyle tips

• Avoid prolonged sitting; stand or walk around regularly.
• Use a donut cushion if it makes sitting more comfortable.
• Keep a clean, dry area — change dressings as advised.
• Do not ignore bowel urgency or constipation — manage it before it becomes a problem.

Diet and exercise

Eat a high-fibre diet with plenty of fruits, vegetables, and whole grains. Drink enough water to keep your stools soft. Gentle exercise, like walking, can help keep bowel movements regular without putting strain on the area.

Mental health and emotional wellbeing

An anal fistula can feel embarrassing, frustrating, and stressful. You may worry about hygiene, relationships, or daily comfort. These feelings are normal. It is important to speak openly with your doctor and to let close family or friends know what you are going through.

Prevention

It is not always possible to prevent an anal fistula, but treating an anal abscess quickly and properly reduces the risk. If you have a condition like Crohn's disease, managing it well under a specialist can lower your chances of developing a fistula.

Complications

If left untreated

• The fistula may spread and create multiple channels.
• Infection can spread to nearby tissues, causing a deeper abscess.
• Rarely, the infection can enter the bloodstream and lead to sepsis, a life-threatening emergency.
• Long-standing fistulas may scar the anal sphincter muscle and affect bowel control.

Long-term outlook

The outlook for an anal fistula is good with timely treatment. Most fistulas heal well after surgery, and for many people the condition does not come back. Your healthcare team will guide you through recovery, and you can expect to return to your usual activities.

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