Treatment of Anal Fissure (Small Split on Posterior Anal Verge)
Begin all patients with a posterior midline anal fissure on comprehensive conservative therapy immediately, which heals 50% of acute fissures within 10-14 days, then escalate to topical calcium channel blockers if no improvement after 2 weeks, and reserve lateral internal sphincterotomy only for chronic fissures that fail 6-8 weeks of medical therapy. 1, 2
Initial Conservative Management (First-Line for All Acute Fissures)
Start treatment immediately with the following combination, as this approach addresses the mechanical trauma component and heals approximately half of acute fissures: 1, 2
- Fiber supplementation: 25-30g daily through diet or supplements to soften stools and minimize anal trauma 1, 2
- Adequate fluid intake: Throughout the day to prevent constipation 1, 2
- Warm sitz baths: 2-3 times daily to promote internal anal sphincter relaxation 1, 2
- Topical analgesics: Lidocaine 5% for pain control as needed 1, 2
Continue this regimen for 10-14 days before escalating therapy. 1
Pharmacologic Therapy (If Conservative Management Fails After 2 Weeks)
If no improvement after 2 weeks of conservative care, the pathophysiology shifts focus to internal anal sphincter hypertonia with decreased anodermal blood flow creating an ischemic environment. 1 Address this with:
First choice: Compounded 0.3% nifedipine with 1.5% lidocaine applied three times daily for at least 6 weeks, which achieves 95% healing rates by reducing internal anal sphincter tone and increasing local blood flow. 1, 2
Alternative option: 2% diltiazem cream applied to the anal verge twice daily for 8 weeks achieves 48-75% healing rates without the headache side effects associated with nitroglycerin. 1, 2
Less preferred option: Topical nitroglycerin (GTN) shows only 25-50% healing rates and causes headaches in many patients, making it inferior to calcium channel blockers. 1, 2
Second-line intervention: Botulinum toxin injection into the internal anal sphincter demonstrates 75-95% cure rates with low morbidity if topical calcium channel blockers fail after 6-8 weeks. 1, 2, 3
Surgical Referral Criteria
Refer for lateral internal sphincterotomy (LIS) only after documented failure of at least 6-8 weeks of comprehensive conservative management including fiber, fluids, sitz baths, and topical pharmacologic therapy. 1, 2
LIS remains the gold standard with >95% healing rates and 1-3% recurrence rates. 1, 2, 3, 4
Exception for early surgical referral: Consider LIS for acute fissures with severe, intractable pain that makes conservative care intolerable. 2
Surgical Risks to Discuss
- Small risk of minor permanent incontinence (significantly lower than the 10-30% rate with manual dilatation) 1, 2
- Wound-related complications (fistula, bleeding, abscess, or non-healing wound) occur in up to 3% of patients 1, 2
Critical Pitfalls to Avoid
Never perform manual anal dilatation—it causes permanent incontinence in 10-30% of patients and is absolutely contraindicated. 1, 2, 5, 4
Do not use hydrocortisone beyond 7 days due to risk of perianal skin thinning and atrophy that worsens the fissure. 1, 2
Do not rush to surgery for acute fissures since 50% heal with conservative management alone. 1, 2
Avoid coconut oil or other superficial lubricants as they provide no pharmacologic action to reduce sphincter tone or increase local blood flow. 1
Red Flags Requiring Urgent Evaluation
Since your fissure is in the posterior midline (typical location), no laboratory tests or imaging are needed and diagnosis is clinical. 2 However, if the fissure were lateral, multiple, or off-midline, this would require immediate investigation for serious underlying pathology including Crohn's disease, HIV/AIDS, ulcerative colitis, tuberculosis, syphilis, leukemia, or anorectal cancer before initiating any treatment. 2, 5
Special Consideration
If you have diarrhea, address this underlying cause first before any surgical intervention, as reducing sphincter tone in the setting of loose stools dramatically increases incontinence risk. 2