Perianal Abscess & Fistula

A perianal abscess is a collection of pus that builds up in the tissue around your back passage, usually because one of the small glands inside the anal canal has become infected. An anal fistula is a small tunnel or channel — often like a tiny burrow — that forms between the inside of the anal canal and the skin around it. Around 30–50% of people who have had an abscess go on to develop a fistula afterwards. Both conditions are common, and both have good treatments available.

An abscess usually comes on quite suddenly. You will likely notice a tender, swollen, red area around your back passage — it can be quite painful. Sometimes a fever or feeling unwell comes with it. The important thing to know is that an abscess will not go away on its own or with antibiotics alone — it needs to be drained. This is done as a day procedure under a general anaesthetic, and relief is usually immediate afterwards. At the same time, Mr Nguyen can examine the area (called an examination under anaesthetic, or EUA) to check whether a fistula has already started to form.

A fistula usually makes itself known through a persistent or on-and-off discharge of fluid from a small opening near your back passage, or through recurring abscesses. It may also cause ongoing discomfort in the area. Fistulas are described by where the tunnel passes in relation to the sphincter muscles (the ring of muscle that controls your ability to hold on) — terms like intersphincteric or transsphincteric describe this. Understanding exactly where the fistula is — sometimes with the help of an MRI scan — is important because it shapes the surgical plan.

Treatment is carefully tailored to your specific situation. The key question is always: how much of the sphincter muscle does the fistula pass through? For a simple, shallow fistula, a procedure called a fistulotomy — where the tunnel is gently laid open — works very well and heals reliably. For a deeper or more complex fistula, where cutting through too much muscle at once could affect your bowel control, the treatment is done in stages. A seton — a soft surgical thread passed through the fistula — is often placed first. Depending on the situation, it may be used to slowly divide the muscle a little at a time (a cutting seton), or simply to keep the tract open and controlled while preparing for a more definitive repair later. Other options for complex fistulas include the LIFT procedure (ligation of the intersphincteric fistula tract — a technique that seals the inner opening without cutting through muscle) and an advancement flap repair (where a small patch of healthy tissue is used to close the internal opening).

If you have Crohn's disease (a type of inflammatory bowel disease), you may be more likely to develop fistulas, and they tend to be more complex. Managing a Crohn's-related fistula involves close teamwork between Mr Nguyen and your gastroenterologist. Treatment usually combines medication for the Crohn's itself with surgical steps like an EUA, seton placement, and careful long-term monitoring.

Protecting your bowel control is the number one priority in every fistula decision Mr Nguyen makes. He uses MRI imaging when needed to map exactly where the fistula is before planning surgery. Simple fistulas are treated definitively; more complex ones are managed in careful stages — usually with a seton first — to keep your continence safe throughout the process. Mr Nguyen will talk you through the whole plan at your consultation, including how many steps are likely and a realistic timeframe. There are no surprises — you will always know what to expect next.

If you have a painful, swollen, red area around your back passage, please seek urgent assessment — this is most likely an abscess and needs to be drained soon. Do not wait for a routine appointment. If you have ongoing discharge from the area, a history of recurrent abscesses, or have been told in the past that you have a fistula, please make an appointment to be reviewed — even if things are not extremely painful right now.

If your GP is concerned about an acute abscess, you may be sent straight to hospital for drainage — this is the immediate priority and gives prompt relief. For a fistula or recurrent symptoms, your GP will send a referral and most patients are seen within one to two weeks. At the consultation, Mr Nguyen will take a careful history, examine the area, and in many cases arrange an examination under anaesthetic and an MRI to map the fistula tract precisely before committing to a definitive plan.

Fistula treatment is often staged. The first step is usually drainage of any active infection, sometimes with a soft seton (a small drainage stitch) left in place to keep things settled while the tissues calm down. Once the inflammation has settled — typically over weeks to months — a definitive repair is planned, with the technique chosen to balance healing the fistula against protecting your continence. A follow-up appointment is arranged after each stage to confirm progress, and Mr Nguyen will keep your GP informed throughout.

If you have questions or would like to be assessed, Mr Ba Nguyen consults at his rooms in Heidelberg and operates at Warringal Private Hospital and Epworth Eastern, Box Hill. A GP or specialist referral is needed to make an appointment.