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perianal abscess

see also:

  • BEWARE: severe pain but no local signs may be due to other anorectal sites such as an intersphincteric abscess!


  • perianal abscesses are abscesses in the soft tissue surrounding the anal canal arising from the anal crypts, initially forming in the intersphincteric space, and are often associated with a fistula tract (fistula-in-ano), particular if the patient has Crohn's disease.
  • 90% are caused by blocked anal glands with no obvious underlying cause
    • thought that tight anal sphincter may contribute to the blockage
  • they account for ~60% of anorectal abscesses with other sites being:
    • ischiorectal 20%, intersphincteric 5%, supralevator 4%, and submucosal 1%
  • most common in 3rd and 4th decades of life but is also quite common in infants
  • affects males 2-3x more than females
  • 30% have a PH of a perianal abscess
  • appears to be more common in Spring and Summer
  • common organisms implicated in abscess formation include E. coli, Enterococci species, and Bacteroides species

less common causes (< 10% of cases)

ED work up

clinical history

inital ED Mx

  • confirm diagnosis by examination finding of tender, peri-anal indurated swelling
  • nil orally
  • iv maintenance fluids
  • analgesia - usually opiates
  • blood glucose level if diabetic
  • contact surgical registrar for admission and definitive Mx in theatre
  • 4/24 obs
  • fluid balance chart
  • DVT prophylaxis
  • consider antibiotics if extensive cellulitis

surgical management

  • as per WH pathway:
    • use anal retractor to look for fistulae but do not lay open fistula tract routinely
    • examine for Crohn's disease by assessing mucosa - biopsy any suspicious mucosa
    • incise abscess and excise non-viable skin
    • culture pus
    • curette cavity
    • do not use H2O2 as risk of gas embolism
    • do not place seton unless patient has Crohn's disease
    • loosely pack cavity with an absorbent alginate dressing for haemostasis initially - remove on day 1 post-op then replace with combine dressing
perianal_abscess.txt · Last modified: 2019/06/26 17:21 (external edit)