Anal Fissure
A painful tear in the lining of the anus, usually caused by hard stool, making bathroom visits feel like "passing glass."
Emergency Management: None specific, though extreme pain may drive urgent care visits.
A small tear or cut in the lining of the anus (anoderm), typically extending from the dentate line to the anal verge.
Detailed Overview
Causes severe, sharp pain during bowel movements, often accompanied by bright red blood. The pain triggers spasm of the internal anal sphincter, which decreases blood flow to the area, preventing healing and creating a vicious cycle of pain, spasm, and ischemia.
Epidemiology & Demographics
Very common, affects all ages but most frequent in young and middle-aged adults. Equal incidence in men and women.
Etiological Mechanism
Trauma to the anal canal, most commonly from passing large, hard stools.
Primary Causes
Constipation, explosive diarrhea, childbirth trauma, or anal intercourse.
Initial mechanical trauma tears the posterior midline anoderm (anterior in some females). The pain induces a hypertonic internal anal sphincter spasm. The resting pressure exceeds the perfusion pressure of the local capillaries, leading to local ischemia at the posterior commissure. This ischemia impairs wound healing, causing the fissure to become chronic (>8 weeks).
Diagnostic Criteria & Guidelines
Visual inspection showing the tear. Digital rectal exam is usually too painful and unnecessary if the fissure is visualized. Lateral fissures should prompt investigation for secondary causes (Crohn's, HIV).
Medical sphincterotomy: Topical Calcium Channel Blockers (e.g., Nifedipine 0.2% ointment or Diltiazem 2% ointment) applied to the anal verge BID for 6-8 weeks to relax the sphincter and increase blood flow. Combined with warm sitz baths (10-15 mins, 3-4 times a day) and a high-fiber diet (25-30g/day) with water.
Second-Line & Adjunctive Therapy
Botulinum toxin type A (Botox) injection (typically 20-50 units) into the internal anal sphincter for cases failing topical therapy.
Surgical & Procedural Management
Lateral internal sphincterotomy (LIS) is the gold standard for refractory chronic fissures. A small portion of the internal sphincter is cut to relieve the spasm permanently.
Patient Counseling & Advice
Warn patients that topical nitroglycerin (an alternative first-line) frequently causes severe headaches. Counsel that LIS has a small risk (1-3%) of mild flatus or fecal incontinence.
Follow-Up & Monitoring Schedule
Follow up in 4-6 weeks to assess for healing. If not healed, consider Botox or surgery.
Preventive Strategies
Maintaining soft, formed stools through adequate hydration and dietary fiber.
Excellent. ~50% heal with supportive care (sitz baths/fiber). >90% heal with LIS if medical therapy fails.