What is the recommended management of an anal fissure?

Management of Anal Fissure

Start all acute anal fissures with conservative management (fiber 25–30 g/day, adequate hydration, warm sitz baths 2–3 times daily, and topical lidocaine 5%), which heals approximately 50% of cases within 10–14 days; if the fissure persists beyond 2 weeks, add compounded 0.3% nifedipine with 1.5% lidocaine applied three times daily for 6–8 weeks (achieving 95% healing), and reserve lateral internal sphincterotomy for chronic fissures that fail this comprehensive medical regimen. 1

Critical First Step: Rule Out Atypical Pathology

Before initiating any treatment, verify that the fissure is located in the posterior midline (90% of typical cases) or anterior midline (10% in women, 1% in men). 1, 2

Red flags requiring urgent evaluation for Crohn's disease, HIV/AIDS, ulcerative colitis, tuberculosis, syphilis, or malignancy:

• Lateral or off-midline fissure location 1, 2
• Multiple fissures 1
• Lack of response to conservative treatment after 8 weeks 1
• Rectal bleeding with anemia or unexplained weight loss 1

Do not treat atypical fissures empirically—halt all therapy and complete a full workup first. 2

Step 1: Conservative Management (First-Line for All Acute Fissures)

Duration: 10–14 days initially, reassess at 2 weeks 1, 3

Components:

• Fiber supplementation: 25–30 g daily (via diet or supplement) to soften stools and minimize anal trauma 1, 2, 3
• Adequate hydration: prevents constipation 1, 2, 3
• Warm sitz baths: 2–3 times daily to promote internal sphincter relaxation 1, 2, 3
• Topical lidocaine 5%: applied to the anal verge for pain control 1, 3
• Oral analgesics (paracetamol or ibuprofen): if topical agents provide inadequate relief 2, 3

Expected outcome: Approximately 50% of acute fissures heal with this regimen alone. 1, 4

Special Consideration: Infected Fissures

If there is evidence of infection or poor genital hygiene, add topical metronidazole cream combined with lidocaine 5% applied three times daily for 4 weeks, which achieves 86% healing compared to 56% with lidocaine alone. 3

Step 2: Pharmacologic Therapy (If No Improvement After 2 Weeks)

Preferred option: Compounded 0.3% nifedipine with 1.5% lidocaine applied to the anal verge three times daily for 6–8 weeks. 1

Mechanism: Blocks L-type calcium channels in internal anal sphincter smooth muscle, reducing sphincter tone and increasing local blood flow to interrupt the pain-spasm-ischemia cycle. 1

Efficacy: 95% healing rate after 6 weeks, with pain relief typically evident after 14 days. 1

Alternative calcium channel blocker: 2% diltiazem cream applied twice daily for 8 weeks achieves 48–75% healing rates with minimal side effects. 1

Less Preferred Option: Topical Nitroglycerin

Glyceryl trinitrate (GTN) 0.2–0.4% applied twice daily achieves only 25–50% healing rates and causes headaches in many patients, making it inferior to calcium channel blockers. 1, 5

Minimally Invasive Option: Botulinum Toxin

Botulinum toxin injection into the internal anal sphincter demonstrates 75–95% cure rates with low morbidity and is a viable second-line treatment, especially for patients at risk for incontinence. 1, 5

Step 3: Surgical Management (After 6–8 Weeks of Failed Medical Therapy)

Lateral internal sphincterotomy (LIS) is the gold standard for chronic fissures unresponsive to comprehensive medical therapy, achieving >95% healing with 1–3% recurrence rates. 1, 6, 4

Indications for LIS:

• Chronic fissures (>8 weeks) that have failed 6–8 weeks of fiber, hydration, sitz baths, and topical calcium channel blocker therapy 1
• Acute fissures with severe, intractable pain that makes conservative care intolerable 1

Technical points:

• Perform the sphincterotomy laterally (at 3 or 9 o'clock position) to prevent keyhole deformity 1
• Divide the internal sphincter to the dentate line to ensure adequate reduction of sphincter tone 1

Risks: Minor permanent continence defects (typically flatus incontinence) occur in approximately 1–10% of patients, though some studies report transient incontinence in up to 45% that resolves in most cases over time. 1, 7

Contraindications to LIS:

• Pre-existing fecal incontinence or weakened sphincter function 1
• Women with anterior fissures (higher incontinence risk) 1
• Patients with Crohn's disease or inflammatory bowel disease 1

Absolutely Contraindicated Intervention

Manual anal dilatation is strongly contraindicated due to unacceptably high permanent incontinence rates of 10–30% from uncontrolled injury to the internal and external anal sphincters. 1, 2, 3, 6

Special Populations

Pregnancy: Prioritize conservative measures (fiber, hydration, sitz baths); topical calcium channel blockers may be used after obstetric consultation. 1

Children: Use the same conservative regimen; reserve surgical intervention for truly refractory cases after prolonged medical therapy to minimize incontinence risk. 1

Common Pitfalls to Avoid

• Do not use hydrocortisone beyond 7 days due to risk of perianal skin thinning and atrophy, which can worsen the fissure. 1
• Do not rush to surgery for acute fissures, as 50% heal with conservative management alone. 1
• Do not presume all anorectal pain is due to hemorrhoids—hemorrhoids primarily present with bleeding and pruritus, not the stinging pain during defecation typical of fissures. 1
• Do not ignore atypical fissure locations—lateral or multiple fissures require urgent evaluation for IBD, cancer, or infection before any treatment. 1, 2

Pathophysiology Context

The internal anal sphincter (not the external sphincter) generates the painful spasm and elevated resting anal pressure (≈114 cm H₂O vs. normal 73 cm H₂O) that diminishes anodermal blood flow, producing local ischemia that impedes healing. 1 All effective treatments—whether pharmacologic or surgical—target reduction of internal anal sphincter tone. 1, 4