Longitudinal split in the squamous epithelium of the anal canal distal to the dentate line.
History taking
- • Severe pain during and after defecation, bright red bleeding on toilet paper
- • Constipation, hard stools, anal spasm
- • Posterior midline most common; lateral fissures suggest Crohn, TB, malignancy
Examination
- • Gentle inspection — visible fissure, sentinel pile, hypertrophied papilla
- • PR exam often deferred due to pain
Red flags
- • Multiple, lateral, painless fissures — investigate for IBD, HIV, syphilis, TB, malignancy
Differential diagnosis
- • Hemorrhoids, perianal abscess, anal cancer, Crohn disease
Recommended investigations
- • Clinical diagnosis; sigmoidoscopy if atypical
Diagnosis
- • Acute (<6 weeks) vs chronic (>6 weeks with skin tag/hypertrophied papilla/internal sphincter visible)
Initial treatment / management
- • Conservative first-line: high-fibre diet, sitz baths, topical analgesics
- • Topical GTN 0.2–0.4% or Diltiazem 2% BD x 6–8 weeks
- • Botox injection or lateral internal sphincterotomy if refractory
Prescription examples
- • Topical Diltiazem 2% — apply to anal margin BD x 6 weeks
- • Tab Ispaghula husk 1 sachet HS
- • Sitz baths warm water TDS
- • Avoid topical lignocaine alone — temporary relief only
Follow-up advice
- • Review at 2–4 weeks; surgery if no healing at 6–8 weeks
Patient counselling
- • High-fibre diet, hydration, avoid straining
- • Topical GTN may cause headache
Referral criteria
- • Chronic fissure, atypical features, suspected IBD/TB/malignancy
Clinical pearls
- • Lateral internal sphincterotomy is gold-standard surgery — small risk of incontinence
- • Always biopsy lateral or atypical fissures
References
- • ASCRS Clinical Practice Guidelines for Anal Fissure 2017
Educational outpatient guide — verify against local guidelines before clinical use.
