Anal fissure

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Anatomy of the anus.
Anatomy of anal fissure.
  • Superficial linear tear of anal canal from at/below dentate line to anal verge
    • May be due to passage of hard stool, frequent diarrhea, or abuse
  • Most common cause of painful rectal bleeding
  • In >90% of cases anal fissures occur in the midline posteriorly
    • Non-healing fissure or one not located in midline suggests alternative diagnosis (e.g. Crohn's, malignancy)

Clinical Findings

Close up photo of anal fissure (at red arrow).
  • Acute sharp, cutting pain most severe during and immediately after bowel movement
    • Subsides between bowel movements (distinguishes fissure from other anorectal disease)
  • Bright red rectal bleeding, small in quantity (usually noticed only on toilet paper)
  • Lateral to anus often indicates associated systemic illness such as Crohn's, HIV, leukemia, TB, syphilis

Differential Diagnosis

Anorectal Disorders

Undifferentiated lower gastrointestinal bleeding



  • Typically clinical (no studies needed)


  • Having patient bear down may make fissure more noticable
  • Sentinel pile, located at distal end of fissure, along with deep ulcer suggests chronicity


  • Warm sitz baths 15 min TID-QID and after each bowel movement
    • Provides symptomatic relief by improving anal blood flow and relieves anal sphincter spasm
  • Topicals
  • High-fiber diet
    • Prevents stricture formation by providing a bulky stool
  • Meticulous anal hygiene is imperative; after defecation anus must be cleaned thoroughly
  • Surgical referral indicated if healing does not occur in a reasonable amount of time



  • Most patients can be managed medically and discharged with outpatient follow-up

See Also

External Links