Anal fistula and pilonidal sinus

Also called Fistula-in-ano, Pilonidal abscess, Perianal abscess

Tunnels and pits that discharge and will not heal. Embarrassment delays presentation, and both are far more treatable than people fear.

What it is

Two separate conditions that behave similarly and cause the same problems: persistent discharge, recurrent abscesses, and a great deal of embarrassment.

**An anal fistula** is a small tunnel between the anal canal and the skin near the anus. It usually follows a perianal abscess, which is an infection of a small gland, and once formed it rarely heals on its own. Fistulas are a common feature of Crohn's disease, and anybody with one should be considered for that.

**A pilonidal sinus** is a pit or tunnel in the natal cleft, at the top of the buttock crease, usually containing hair. It affects young adults, more often men, and is associated with sitting for long periods, which is why it was once called jeep driver's disease.

Both cause recurrent painful abscesses that need draining, and a chronic discharging opening between episodes.

Treatment is surgical and varies considerably, from laying the tract open to newer sphincter-preserving techniques for fistulas, and from wide excision to minimally invasive approaches for pilonidal disease. Recurrence is common, and the choice of operation matters.

An acute abscess needs draining urgently; antibiotics alone will not treat it.

Signs you might notice

Anal fistula: persistent discharge of pus or blood near the anus, often staining underwear; a tender lump or opening; recurrent abscesses; pain, particularly on sitting or opening the bowels; and sometimes discharge of stool through the opening.

Pilonidal sinus: one or more small pits at the top of the buttock crease, often with hair; discharge; recurrent painful swellings; and a chronic aching in the area.

Both: pain that is severe during an abscess and much improved once it is drained.

Urgent, same day: increasing pain, swelling, redness, fever, or difficulty passing urine, which suggests an abscess needing drainage.

999 or A and E: rapidly spreading redness, severe pain out of proportion, fever and feeling very unwell, which may be a severe perineal infection. See necrotising fasciitis.

How it can affect day-to-day life

Embarrassment is the dominant feature. People live with discharge, pads and recurrent pain for months or years without seeking help, and are frequently astonished at how matter-of-fact clinicians are about it.

Sitting is the main practical problem, affecting work, driving and study, and a cushion with a cut-out helps.

Wound care after surgery is prolonged: open wounds in this area take weeks to months to heal and need regular dressing, usually by district or practice nurses.

For pilonidal disease, hair removal from the area reduces recurrence, and is one of the few things within the person's control.

For fistulas, the trade-off between fully curing the fistula and preserving continence is the central surgical decision, and it should be discussed explicitly, because incontinence after fistula surgery is a real and life-changing risk.

Anybody with a fistula should be asked about bowel symptoms, because Crohn's disease presents this way.

Supporting someone well

Go and get it looked at. It is a common, ordinary problem and nobody will be surprised.

Get an acute abscess drained urgently; antibiotics alone are not enough.

Ask about Crohn's disease if you have a fistula, especially with any bowel symptoms.

Ask about sphincter-preserving options and about the risk to continence before agreeing to fistula surgery.

For pilonidal disease, keep the area clean and dry and ask about hair removal to reduce recurrence.

Arrange district or practice nurse wound care before discharge after surgery.

Use a cushion with a cut-out for sitting.

Keep stools soft to reduce pain and trauma; see constipation.

Get spreading redness with fever seen as an emergency.

Where to get help

A GP practice for assessment and referral to colorectal surgery.

Urgent care or A and E for an acute abscess.

District or practice nurses for wound care afterwards.

Guts UK and Crohn's and Colitis UK for information, particularly where Crohn's is involved.