Benign Anorectal Pathology

In this article, we cover common benign anorectal pathologies including haemorrhoids, fissures & fistulas with a quick overview of their assessment & management.

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Basic anatomy

  • Anatomical position of anus is described by a clock in the lithotomy position (lying on back with legs apart, pubic symphysis is 12 o’clock, coccyx is 6 o’clock)
  • Internal anal sphincter – surrounds upper 2/3rds of anal canal. Involuntary. Smooth muscle.
  • External anal sphincter – surronds lower 2/3rds of anal canal. Voluntary. Skeletal muscle
  • Pectinate line

Haemorrhoids (Piles)

  • What is it?
    • Swollen vein in lower rectum
  • How does it present?
    • Painless PR bleeding in bowl/on wiping. Itching.
    • Pain if thrombosed
  • Risk factors
    • Heavy lifting, prolonged sitting, obesity, constipation, pregnancy
  • Diagnosis
    • PR examination (typically impalpable but occasionally visible), proctoscopy
  • Treatment
    • Conservative: sitz bath, dietary fibre, hydration
    • Medical: Anusol, stool softners, (topical GTN if thrombosed)
    • Surgical: Haemorroidectomy (thrombectomy). Band ligation/sclerotherapy 

Fissure in Ano (Anal Fissures)

  • What is it?
    • A mucocutaneous defect of the anal canal (a tear)
  • How does it present?
    • Painful PR bleeding (why is it painful?)
  • Risk factors
    • Mostly idiopathic (90%)
    • Constipation, Crohn’s, tuberculosis
  • Diagnosis?
    • PR examination (90% posterior midline), EUA
  • Management?
    • Conservative – stool softners, fibre, hydration
    • Medical – topical GTN (0.2%) or diltiazem (2%). Botulinum toxin injection.
    • Surgical  – lateral sphincterotomy (10% incontinence to flatus) , advancement flaps

Fistula in Ano (Anal Fistulas)

  • What is it?
    • Abnormal connection between two epithelial surfaces (rectum+skin with 2x openings)
  • How does it present?
  • Risk factors
    • Crohn’s, tuberculosis, diabetes, HIV
  • Diagnosis?
    • PR examination 
    • EUA, MRI
  • Goodsall’s rule
    • Within 3cm of the anus, anterior openings will follow a straight line into the anal canal, which posterior openings will curve towards the midline and then enter the
    • Of clinical importance when trying to find the internal openings during surgery (via PR and using a Lockhart-mummery probe)
  •  Management
    • Abscess -> I&D (secondary intention) +/- sepsis 6
    • Fistula usually once infection resolves (if it was present):
      • Fibrin glue (50% failure)
      • Seton 
      • Fistulotomy “lay open” (CI: Crohn’s, high tract)
      • Complex surgery (advancement flaps)

Written by Dr Marc Huttman (FY2)

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