Perianal Abscess Surgery

What is a perianal abscess?

An abscess is a collection of pus and is usually caused by the body’s reaction to an infection. Abscesses can arise in the perianal area due to infection of the anal glands or the skin around the anus.

They present as a painful lump or swelling around the anus. If they burst, they can present with discharge of pus and blood.

If the abscess arises from the perianal glands, it may be associated with an underlying anal fistula. This can be a cause of recurrent abscess formation.

What does surgery involve?

A perianal abscess requires incision and drainage under a general anaesthetic. At the same time, the surgeon looks for an underlying fistula which may need treatment at the same time. This may involve a fistulotomy or insertion of a seton.

After drainage of an abscess, the skin cannot be closed over the abscess cavity or else the abscess forms back. It is left open and heals from inside out.

What are the risks of surgery?

The risk of significant bleeding is minimal.

Inadequate drainage of the abscess may cause an early recurrence.

If there is an underlying fistula tract that cannot be detected (due to the inflammation), the abscess may recur in the future.

If too much of the anal sphincter muscle is divided during abscess drainage, incontinence is possible. This is rare, however, and usually happens in the context of performing a fistulotomy at the same time.

Before surgery

A perianal abscess is a surgical emergency and you will be admitted to hospital usually through the emergency department with perianal pain and / or discharge.

You will need to be fasting for at least 6 hours from food and at least 4 hours from water or other clear fluids in order to have a safe anaesthetic.

After surgery

The abscess cavity may require daily packing with gauze or a so-called alginate dressing (Kaltostat) for days to weeks before closing completely.

The duration of packing depends on the size of the abscess cavity. You do not have to be in hospital all this time as packing is usually done either at home by Hospital In The Home or District Nursing services or at your local doctor’s clinic.

You can have a shower before the dressings are changed. If you open your bowels and the packing comes out, do not panic. It is best to have a shower or wash it with water then place a pad over it until the next dressing change.

A minor degree of blood oozing from the abscess cavity is normal until the cavity closes completely. You may need to wear a pad to prevent staining of your underwear.

Ladies’ sanitary pads work well for this purpose and can be used by men and women.

Pain is usually only experienced the first few times during a dressing change. It is usually much better than the pain experienced before draining the abscess. Some degree of pain or stinging may last for up to four weeks after surgery (especially following defecation).

You should take regular Panadol (as long as there are no medical reasons for you not to take it such as an allergic reaction or liver disease).

Non-steroidal anti-inflammatory medication such as Neurofen and Voltaren can also help with pain and inflammation but should be taken on a full stomach. Take these for the first 3-5 days as required.

Stronger pain killers such as opioid anaelgesics (Endone, Codeine) may help in the first couple of days but should be taken sparingly as they can cause constipation which results in more pain when opening your bowels.

It is very important to maintain soft stools after surgery. This is done by having an adequate intake of fluid and fibre (see Prevention of constipation) as well as taking regular Movicol (1 sachet 1-3 times a day).

Laxatives such as lactulose or coloxyl are not advisable as diarrhoea can worsen the pain post haemorrhoidectomy. The aim is to have soft stools NOT loose watery stools.

Most patients are worried about opening their bowels especially for the first time. You should not let fear of pain stop you from opening your bowels as this will only make things worse by hardening the stools and causing a spasm of the anal muscles.

If you are finding it difficult to pass soft stools, it may be due to a spasm of the anal sphincter. This can be treated with topical Rectogesic ointment 2-3 times a day. This is an over-the-counter ointment that should be applied into the first 1-2cm of the anus. The easiest way to do this is to wear a disposable non-sterile glove (plastic food-handling gloves are ok) then apply 1.5cm of the ointment using your index finger.

Most patients can go home the same day after draining their abscess. However, it may be necessary to stay in hospital for the administration of intravenous antibiotics if there is significant infection around the abscess cavity (cellulitis).

Follow up with your surgeon is usually within 4 weeks of your operation. You will be given an appointment before leaving the hospital.