Workup and Treatment for Anal Fissure
Initial Diagnostic Approach
For typical acute anal fissures presenting in the posterior midline, clinical examination alone is sufficient—no routine laboratory or imaging studies are needed. 1, 2
Key Diagnostic Features to Identify:
- Examine fissure location by effacing the anal canal with opposing traction on the buttocks 2
- Typical fissures occur in the posterior midline in 90% of cases; anterior fissures occur in 10% of women versus 1% of men 1
- Red flags requiring further workup include: 1, 2, 3
- Lateral or multiple fissures (suspect IBD, HIV, syphilis, herpes, anorectal cancer, or tuberculosis)
- Signs of chronicity (sentinel tag, hypertrophied papilla, visible internal sphincter muscle)
- Systemic symptoms or signs of perianal sepsis
- No response to conservative treatment after 8 weeks
When to Order Imaging:
Only pursue endoscopy, CT, MRI, or endoanal ultrasound for atypical presentations with suspected inflammatory bowel disease, anal cancer, or occult perianal sepsis. 1, 3
Treatment Algorithm for Acute Anal Fissures
First-Line Conservative Management (0-2 Weeks)
All acute anal fissures should receive non-operative management as first-line treatment, which heals approximately 50% of cases within 10-14 days. 1, 2
Implement the following simultaneously: 1, 2, 3
- Fiber supplementation: 25-30g daily to soften stools and minimize anal trauma
- Adequate fluid intake to prevent constipation
- Warm sitz baths to promote sphincter relaxation and local blood flow
- Topical anesthetics: Lidocaine 5% applied directly to the fissure for pain control
- Oral analgesics: Paracetamol if topical agents provide inadequate relief
Critical pitfall to avoid: Manual dilatation is absolutely contraindicated due to unacceptably high permanent incontinence rates of 10-30%. 1, 2, 3
Second-Line Pharmacologic Management (After 2 Weeks Without Improvement)
If no improvement after 2 weeks of conservative management, initiate topical calcium channel blockers as the preferred pharmacologic option. 2, 3
Recommended pharmacologic agents in order of preference:
Compounded 0.3% nifedipine with 1.5% lidocaine applied three times daily achieves 95% healing after 6 weeks with minimal side effects 2
Compounded 2% diltiazem cream applied to the anal verge twice daily for 8 weeks achieves healing rates of 48-75% without headache side effects 2
Topical nitroglycerin (GTN) shows only 25-50% healing rates and causes headaches in many patients, making it a less favorable option 2, 4
Botulinum toxin injection demonstrates 75-95% cure rates with low morbidity and only transitory mild fecal incontinence 2, 4
Mechanism of action: These agents reduce internal anal sphincter tone and increase local blood flow, addressing the underlying pathophysiology of sphincter hypertonia and ischemia. 1, 2
Important warning: Hydrocortisone should not be used beyond 7 days due to risk of perianal skin thinning and atrophy, which can worsen the fissure. 2
Surgical Management (After 6-8 Weeks of Failed Medical Therapy)
Lateral internal sphincterotomy (LIS) remains the gold standard for chronic fissures unresponsive to 6-8 weeks of medical therapy, with >95% healing rates and 1-3% recurrence rates. 2, 4, 5, 6
Indications for surgical referral: 2, 3, 5
- Chronic fissures with documented failure of at least 6-8 weeks of conservative management including fiber supplementation, adequate fluid intake, warm sitz baths, and topical pharmacologic agents
- Acute fissures with severe pain that makes conservative care intolerable
- Recurrent fissures despite optimal medical treatment
Surgical risks to discuss with patients: 2, 4
- Small risk of minor permanent incontinence (significantly lower than the 10-30% rate with manual dilatation)
- Wound-related complications (fistula, bleeding, abscess, non-healing wound) occur in up to 3% of patients
Absolute contraindications to surgery: 2, 3
- Acute anal fissures (surgery should never be performed without first attempting conservative management)
- Atypical pathology not yet ruled out
Special Consideration: Low Pressure Anal Fissures with Anal Atony
If anal atony is suspected (atypical presentation suggesting neurologic disease, prior sphincter injury, or IBD), focus exclusively on conservative management and avoid ALL sphincter-relaxing agents. 7
In these rare cases: 7
- Continue fiber supplementation, adequate hydration, warm sitz baths, and topical anesthetics indefinitely
- Absolutely avoid: topical calcium channel blockers (nifedipine, diltiazem), topical nitroglycerin, botulinum toxin injections, and lateral internal sphincterotomy—all would worsen incontinence
- Investigate for serious underlying pathology with endoscopy, CT, MRI, or endoanal ultrasound to rule out Crohn's disease, anal cancer, or occult perianal sepsis
Common Pitfalls to Avoid
Never perform manual dilatation—it causes permanent incontinence in 10-30% of patients 1, 2, 3
Never rush to surgery for acute fissures—50% heal with conservative management alone 1, 2, 3
Never use hydrocortisone beyond 7 days—it causes perianal skin thinning and atrophy 2
Never ignore atypical fissure locations—lateral or multiple fissures require urgent evaluation for IBD, cancer, or infection 1, 2, 3
Never use sphincter-relaxing agents in patients with anal atony—this guarantees incontinence 7