Anal Fissure and Fistula

Anal Fissure and Fistula


  • A longitudinal split in the distal anal canal; extends from the anal verge proximally towards dentate line
  • Posterior fissures (most common) – passage of hard stool
  • Anterior fissures – more common in women following vaginal delivery
  • Fissure away from midline – Crohn’s disease, tuberculosis, STDs, HIV, Kaposi’s sarcoma, squamous cell carcinoma
  • Severe anal pain associated with defaecation
  • Stools are hard, pellet like and there is a drop or streaks of fresh (bright red) blood
  • Mucus discharge
  • Sentinel pile – tag of skin at the outer end of chronic fissures
  • Per-rectal examination with lignocaine jelly – can demonstrate sphincter spasm
  • Proctoscopy is contraindicated


  • Conservative: stool softeners, high fibre diet, mild laxatives, sitz bath
  • Pharmacological
  • Topical Lignocaine gel
  • Topical 0.2% Glyceryl trinitrate – releases NO and relaxes internal sphincter (head ache is a complication)
  • Oral Nifedipine
  • Injection Botulinum A toxin


  • Lateral sphincterotomy – gold standard
  • Fissurectomy and local advancement flap – for chronic, non-healing fissure 


  • An abnormal communication between anal canal and recto with exterior
  • Even though multiple openings are seen in perianal skin – the internal opening is always single
  • Causes: persistent anal gland infection, TB, Crohn’s disease, lymphogranuloma venereum, actinomycosis, rectal duplication, foreign body and malignancy
  • More common in men
  • Usual presentation – intermittent purulent discharge (may be bloody) and pain (which increases until temporary relief occurs when the pus discharges)
  • previous episode of acute anorectal sepsis that settled (incompletely) spontaneously or with antibiotics, or which was surgically drained 

Parks classification

  • Inter-sphincteric (45%) – do not cross external sphincter
  • Trans-sphincteric (40%) – have a primary track that crosses both internal and external sphincters, which then passes through the ischiorectal fossa to reach the skin of the buttock
  • Supra-sphincteric – rare; internal opening above anorectal bundle; usually result from pelvic disease or trauma
  • Goodsall’s rule (used to indicate the likely position of the internal opening according to the position of the external opening)
  • Fistula with external opening in the anterior half of the anus within 3.75 cm – direct type
  • Fistula with external opening in the posterior half of the anus– indirect, curved or horseshoe type


  • Endoanal ultrasound with hydrogen peroxide – to delineate fistulae
  • MRI – Gold standard for fistula imaging
  • Fistulography and CT – useful techniques if an extrasphincteric fistula is suspected

Exam Question

  • Intersphincteric fistula is the most common type of ‘fistula in ano’. 
  • Anal fissure is best diagnosed by characteristic history of bleeding PR and pain during defecation and clinical examination.
  • Treatment of acute fissure in ano : Conservative , Dilatation under GA  , Lateral sphincterotomy.
  • Fistula in ano  is not a cause of acute anal pain.
  • Sentinel pile indicates Anal Fissure.
  • Rectal examination should not be done in Anal Fissure.
  • The treatment of choice in fistula in ano is Fistulotomy.
  • Internal sphincterotomy is the treatment of choice for Fissure in Ano.
  • High or low fistula in ano is termed according to its internal opening present with reference to Anorectal ring.
  • Multiple fistula in ano commonly occurs in Tuberculosis and LGV.
  • Lateral internal sphincterotomy is useful for Anal Fissure.
Don’t Forget to Solve all the previous Year Question asked on Anal Fissure and Fistula

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