Incision and drainage of perianal abscess with or without treatment of anal fistula: Cochrane systematic review

Abstract

Assessed as up to date: 2010/01/29

Background

The perianal abscess is a common surgical problem. A third of perianal abscesses may manifest a fistula-in-ano which increases the risk of abscess recurrence requiring repeat surgical drainage. Treating the fistula at the same time as incision and drainage of the abscess may reduce the likelihood of recurrent abscess and the need for repeat surgery. However, this could affect sphincter function in some patients who may not have later developed a fistula-in-ano.

Objectives

We aimed to review the available randomised controlled trial evidence comparing incision and drainage of perianal abscess with or without fistula treatment.

Search methods

Randomised trials were identified from MEDLINE, EMBASE, the Cochrane Library, and reference lists of published papers and reviews.

Selection criteria

Trials comparing outcome after fistula surgery with drainage of perianal abscess compared with drainage alone were included in the review.

Data collection and analysis

The primary outcomes were recurrent or persistent abscess/fistula which may require repeat surgery and short-term and long-term incontinence. Secondary outcomes were duration of hospitalisation, duration of wound healing, postoperative pain, quality of life scores. For dichotomous variables, relative risks and their confidence intervals were calculated.

Main results

We identified six trials, involving 479 subjects, comparing incision and drainage of perianal abscess alone versus incision and drainage with fistula treatment. Metaanalysis showed a significant reduction in recurrence, persistent abscess/fistula or repeat surgery in favour of fistula surgery at the time of abscess incision and drainage (RR=0.13, 95% Confidence Interval of RR = 0.07-0.24). Transient manometric reduction in anal sphincter pressures, without clinical incontinence, may occur after treatment of low fistulae with abscess drainage. Incontinence at one year following drainage with fistula surgery was not statistically significant (pooled RR 3.06, 95% Confidence Interval 0.7-13.45) with heterogeneity demonstrable between the trials (Chi2 =5.39,df=3, p=0.14, I2 =44.4%).

Authors' conclusions

The published evidence shows fistula surgery with abscess drainage significantly reduces recurrence or persistence of abscess/fistula, or the need for repeat surgery. There was no statistically significant evidence of incontinence following fistula surgery with abscess drainage. This intervention may be recommended in carefully selected patients.

Author(s)

Malik Ali Irqam, Nelson Richard L, Tou Samson

Summary

Treatment of an anal fistula at the same time as drainage of perianal abscess reduces the chances of recurrent abscess and repeat surgery.

  A perianal abscess produces severe pain at or near the back passage (anus) due to an infection with collection of pus (abscess). The treatment is an urgent operation to incise the skin near the anus and drain the pus which relieves the pain. Some patients with a perianal abscess have an associated tunnel called a fistula which connects the anus to the adjacent skin. A fistula can cause problems such as leakage (discharge) from the skin near the anus or may produce a recurrent abscess, and therefore usually requires a repeat operation for its treatment. For this reason it has been proposed that fistula treatment at the same time as drainage of a perianal abscess may be better for patients. This systematic review assesses randomised trials that have addressed the benefits and risks of combined treatment of perianal abscesses and fistulae. Six studies have been published on this topic. The analyses show that combined treatment reduces the risk of persistent abscess or fistula, or repeat surgery without a statistically significant increase in postoperative incontinence.

Reviewer's Conclusions

Implications for practice

Fistula surgery at the time of incision and drainage of a perianal abscess significantly reduces the likelihood of persistent fistula or abscess and the need for repeat surgery. A small number of patients may get transient incontinence following abscess drainage with fistula treatment. The evidence that patients may get minor incontinence for longer following fistula surgery with abscess drainage remains weak. Our findings should not be applied to patients with high or suprasphincteric anal fistulae or other groups (anterior fistulae in female, previous anorectal surgery or trauma, IBD, HIV) at high risk for continence issues.

Implications for research

A RCT larger than those published to date would be required to clarify the risk of minor incontinence following fistula surgery with abscess drainage. This would ideally need to focus on low fistulae, at most including those involving the lower third of the anal sphincter. Also the randomisation should be done intraoperatively once a fistula opening has been demonstrated and blinded follow up applied with quality of life included in the outcomes.

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