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Anal Fissure

Description:
- Longitudinal tear in anal canal lining distal to dentate line, most commonly posterior midline.
- Characterized by knifelike tearing pain on defecation and bright red blood per rectum.
- Can be acute or chronic (>4-8 weeks).
- Chronic fissures may have hypertrophic papilla and sentinel pile (skin tag).

Epidemiology

  • Affects all ages; common in infants 6-24 months (self-limited).
  • Uncommon in older children—consider abuse/trauma.
  • Elderly less common due to lower resting anal pressure.
  • Male = female; women more likely to have anterior midline fissures (25% vs 8%).
  • Lifetime risk ~7.8% in US (similar to appendectomy) (2).
  • Prevalence: 80% infants; 10-20% adults (most untreated medically).

ALERT:
- Lateral fissures: rule out infection.
- Atypical fissures: rule out Crohn disease.

Etiology and Pathophysiology

  • High resting pressure of internal anal sphincter + decreased perfusion → ischemia of anoderm → mucosal splitting during defecation + internal sphincter spasm.

Risk Factors

  • Constipation (25%)
  • Diarrhea (6%)
  • Passage of hard/large stools
  • Low fiber diet
  • Prolonged sitting, obesity (high anal sphincter tone)
  • Trauma (sexual, abuse, foreign body, childbirth, biking)
  • Prior anal surgery with scarring/stenosis
  • Inflammatory bowel disease (Crohn)
  • Infection (chlamydia, syphilis, herpes, TB)

General Prevention

  • Prevent constipation; avoid straining and prolonged sitting.

Commonly Associated Conditions

  • Posterior midline fissures: constipation, IBS
  • Multiple locations: Crohn disease, tuberculosis, leukemia, HIV

Diagnosis

History

  • Severe sharp rectal pain with and after defecation.
  • Bright red blood on stool or wiping.
  • Occasional pruritus or perianal irritation.

Physical Exam

  • Gentle buttock separation reveals tender, smooth-edged tear, usually posterior midline.
  • Digital exam and anoscopy painful, may be deferred if diagnosis clear.
  • Chronic fissures: rolled edges, exposed muscle fibers, hypertrophic papilla, sentinel pile.

Differential Diagnosis

  • Thrombosed external hemorrhoid: painful swollen anal mass.
  • Perirectal abscess: tender, warm erythema, induration.
  • Perianal fistula: abnormal tract with feculent/purulent drainage.
  • Pruritus ani: excoriations and erythema, no true fissure.

Diagnostic Tests & Interpretation

  • Avoid anoscopy/sigmoidoscopy initially unless needed for differential or chronic fissures.
  • Pain may necessitate exam under anesthesia for diagnosis confirmation.

Treatment

Goal:
- Reduce repeated mucosal tearing and internal sphincter spasm.

General Measures

  • Gentle washing with warm water.
  • High-fiber diet, increased fluids, fiber supplements.
  • Avoid constipation and maintain healthy weight.

Medication

First Line (Acute fissures)

  • 50% heal spontaneously with conservative care (1)[C].
  • Stool softeners (docusate).
  • Osmotic laxatives (polyethylene glycol) as needed.
  • Fiber supplements (psyllium, methylcellulose).
  • Topical analgesics (2% lidocaine gel) 2-3x daily.
  • Topical lubricants/emollients (Balneol, glycerin, petroleum jelly).
  • Short-term topical hydrocortisone 1% for inflammation/pruritus.
  • Sitz baths 10-20 minutes, 2-3x daily after defecation.

Second Line (Chronic fissures)

  • Chemical sphincterotomy:
  • Topical nitroglycerin 0.2-0.4% ointment BID (Rectiv 0.4% ointment available).
  • Mechanism: nitric oxide release → vasodilation → reduces resting anal pressure.
  • Side effects: headache, hypotension, dizziness (20-30%).
  • Topical calcium channel blockers (nifedipine 0.2-0.3% gel, diltiazem 2% ointment) 2-4x daily.
  • Equally effective as nitrates, fewer side effects (1)[C].
  • Botulinum toxin (Botox) 20 units injected into internal sphincter: similar healing to nitrates, fewer side effects (3)[C].

Issues for Referral

  • Symptoms persisting after 90-120 days of medical therapy.
  • Late recurrence (50%), especially if underlying cause untreated.
  • Suspected infectious or IBD-related fissures.

Additional Therapies

  • Anococcygeal support (modified toilet seat) may help avoid surgery in chronic fissures.

Surgery/Other Procedures

  • Reserved for medical therapy failure.
  • Lateral internal sphincterotomy (LIS): divides internal sphincter, ~95% healing (1)[C].
  • Risks: fecal/flatus incontinence (short-term 5-47%, long-term 15%).
  • Open and closed LIS techniques similar outcomes (1)[C].
  • Not recommended in women of childbearing age due to incontinence risk.
  • Cutaneous flap for LIS in patients without hypertonia: less incontinence but lower healing rates (1)[C].
  • Botulinum toxin injections: less effective (60-80% healing) than surgery, fewer complications (3)[C].
  • Controlled pneumatic balloon dilation (gastroenterology): not first-line; benefits unclear.

Complementary & Alternative Medicine

  • Herbal remedies (hibiscus, clove, coconut oil, essential oils), anal self-massage require further study before recommendation.

Ongoing Care

Diet

  • High fiber (>25 g/day), increased fluids, reduced caffeine.

Patient Education

  • Avoid prolonged sitting/straining; maintain hydration; avoid constipation; lose weight if obese.
  • Avoid triple antibiotic ointment and long-term steroid creams on anus.
  • Apply nitroglycerin ointment with finger cot/glove; first dose at bedtime to minimize side effects.
  • Apply topical meds directly to anal verge; no need for rectal insertion.

Prognosis

  • Most acute fissures heal within 6 weeks with conservative care.
  • Chronic fissures: ~40% failure rate with medical therapy but remain first-line.

Complications

  • Chronic fissure (nonhealing acute fissure).
  • Recurrence common if underlying cause untreated.
  • Abscess and fistula formation less common.
  • Fecal/flatus incontinence mainly after surgery (5-47% short term, up to 8% long term).

References

  1. Stewart DB Sr, et al. Clinical practice guideline for anal fissures. Dis Colon Rectum. 2017;60(1):7-14.
  2. Salati SA. Anal fissure update. Pol Przegl Chir. 2021;93(4):46-56.
  3. Wald A, et al. ACG clinical guideline: benign anorectal disorders. Am J Gastroenterol. 2014;109(8):1141-57.
  4. Lin JX, et al. Botulinum toxin dosing for chronic anal fissure: meta-analysis. Dis Colon Rectum. 2016;59(9):886-94.

Additional Reading

  • Fargo MV, Latimer KM. Common anorectal conditions. Am Fam Physician. 2012;85(6):624-30.
  • Sugerman DT. JAMA patient page: anal fissure. JAMA. 2014;311(11):1171.

ICD10 Codes

  • K60.2 Anal fissure, unspecified
  • K60.0 Acute anal fissure
  • K60.1 Chronic anal fissure

Clinical Pearls

  • Avoid anoscopy/sigmoidoscopy initially unless necessary for differential diagnosis (e.g., secondary fissures).
  • Best recurrence prevention is treating underlying causes (e.g., constipation).
  • No medical therapy equals surgery in cure and recurrence reduction for chronic fissures.