Description

Anal fissure (fissure in ano): longitudinal tear in the lining of the anal canal distal to the dentate line, most commonly at the posterior midline; characterized by a knifelike tearing sensation on defecation, often associated with bright red blood per rectum; this common benign anorectal condition is often confused with hemorrhoids; may be acute or chronic (>4–8 weeks in duration) and may be associated with the presence of hypertrophic papilla and sentinel pile (skin tag)

Epidemiology

• Affects all ages; common in infants 6 to 24 months; not common in older children, suspect abuse or trauma; elderly less common due to lower resting pressure in the anal canal
• Sex: male = female; women more likely to get anterior midline fissures (25%) versus men (8%)

Etiology and Pathophysiology

High resting pressure within the anal canal (usually as a result of constipation/straining) coupled with decreased perfusion of the posterior canal leads to ischemia of the anoderm, resulting in splitting of the anal mucosa that extends from the dentate line toward the anal verge during defecation and spasm of the exposed internal sphincter.

Risk Factors

• Constipation (25% of patients)
• Diarrhea (6% of patients)
• Passage of hard or large-caliber stool
• Low fiber diet
• High resting pressure of internal anal sphincter (prolonged sitting, obesity)
• Trauma (sexual activity or abuse, foreign body, childbirth, mountain biking)
• Prior anal surgery with scarring/stenosis
• Inflammatory bowel disease (Crohn disease)
• Infection (chlamydia, syphilis, herpes, tuberculosis)
• Hirschsprung disease (congenital absence of distal colonic ganglion cells causing chronic constipation)

General Prevention

All measures to prevent constipation; avoid straining and prolonged sitting on toilet.

Commonly Associated Conditions

Posterior midline location: constipation from any cause, including irritable bowel syndrome (IBS); other multiple locations: Crohn disease, tuberculosis, leukemia, and HIV

History

• Severe, sharp rectal pain, often with and following defecation but can be continuous; bright red blood on the stool or on the paper when wiping
• Occasionally, anal pruritus or perianal irritation

Physical Exam

• Gentle retraction of the buttocks with close inspection of the anal verge will reveal a tender, smooth-edged tear in the anodermal tissue, typically posterior midline, occasionally anterior midline, rarely eccentric to midline. Digital rectal exam and anoscopy are painful and can be deferred if inspection confirms the diagnosis.
• Minimal edema, erythema, or bleeding may be seen.
• Chronic fissures may demonstrate rolled edges, exposed muscle fibers, hypertrophic papillae at proximal end, and a sentinel pile (tag) at distal end.

Differential Diagnosis

• Thrombosed external hemorrhoid: tender, firm, blue-purple nodule at anal verge
• Perirectal abscess: tender, warm erythematous induration or fluctuant mass
• Perianal fistula (abnormal communication between rectum and perianal epithelium): a small opening with feculent or purulent drainage; possible erythema/edema of surrounding skin
• Pruritus ani: shallow perianal excoriations and erythema

Diagnostic Tests & Interpretation

General Measures

• Wash area gently with warm water; consume a high-fiber diet, increase fluids, add daily fiber supplement and stool softener; avoid constipation and maintain healthy weight.
• Medical therapy for chronic fissures is usually initiated in a stepwise manner when needed: topical nitrates, topical calcium channel blockers, botulinum toxin injections.

Medication

Issues for Referral

• Persistent symptoms despite medical therapy, which is usually tried for 90 to 120 days prior to colorectal surgery referral. Select patients with chronic fissures may be referred directly for surgical therapy due to proven superior healing rates (1)[C].
• Late recurrence, which is common (50%) particularly if the underlying issue remains untreated (constipation, IBS)
• Secondary fissures (suspected infectious or inflammatory bowel disease [IBD])

Additional Therapies

Anococcygeal support (modified toilet seat) may offer an advantage in chronic fissures to avoid surgery.

Surgery/Other Procedures

• Surgery is typically reserved for failure of medical therapy (chronic/recurrent anal fissures).
• Lateral internal sphincterotomy (LIS) involves division of the internal sphincter muscle and is the surgical procedure of choice (95% healing rate) (1)[C].
  • Risk for fecal or flatus incontinence: up to 47% short term, up to 15% long term
  • Open and closed techniques have similar results and are equally acceptable (1)[C].
  • May be repeated for recurrent fissures with similar outcomes (1)[C]
  • Not typically performed on women of childbearing potential due to increased risk of fecal incontinence with or without subsequent obstetrical injury (1)
• Anocutaneous flap safe alternative to LIS in patients without anal hypertonia; less incontinence but lower healing rates (1)[C]
• Botulinum toxin injections also first-line treatment; less effective (60–80% healing) than surgery but fewer complications
  • Risk for fecal or flatus incontinence: 18% short term, reversible
  • May be repeated as needed with same efficacy, which varies based on dose and injection site; higher doses and injection out of fissure conferred both higher healing rates and higher complication rates (namely, fecal and flatal incontinence)
  • Higher doses combined with fissurectomy may be as effective as surgical sphincterotomy.
• Controlled pneumatic balloon dilation may be used by gastroenterologists if surgical referral is not available; should not be used first line as benefits are not well documented. Uncontrolled manual dilation is no longer recommended.

Complementary & Alternative Medicine

Alternative therapies (hibiscus and other herbal extracts, clove and coconut oil, essential oils, homeopathic and ayurvedic medications, anal self-massage) need further study before they can be recommended as first-line treatment.

Follow-up Recommendations

Prevention of anal fissures is recommended by addressing patient-specific issues that predispose to constipation (diet, dehydration, medication side effects, sedentarism, etc.).

Diet

High fiber (>25 g/day; augment with daily fiber supplements); increase water/fluid intake, decrease caffeine and alcohol intake.

Patient Education

• Avoid prolonged sitting or straining during bowel movements; drink plenty of fluids; treat constipation with osmotic laxatives; increase physical activity; adopt a weight loss plan if obese.
• Avoid use of triple antibiotic ointment and long-term use of steroid creams to the anal area.
• Use a finger cot or glove when applying nitroglycerin ointment and apply the first dose before bedtime to minimize side effects.
• Topical medications should be applied directly to anal verge; no need to insert rectally

Prognosis

Most acute fissures heal within 6 weeks with conservative medical therapy. Medical therapy is less likely to be successful for chronic anal fissures (40% failure rate) but should remain first-line treatment.

Complications

• Chronic fissure is a complication of nonhealing acute fissure.
• Recurrence is a common complication especially when the underlying cause (constipation/straining) is not addressed.
• Abscess and fistula formation are less common complications.
• Fecal and flatal incontinence is more commonly associated with surgery (5–47% postop), which may become permanent (up to 8% long term, primarily to flatus).

Additional Reading

American Neurogastroenterology and Motility Society. Anal fissure. https://motilitysociety.org/pdf/brochures/anal_fissure_handout.pdf.

ICD-10

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

SNOMED

• 30037006 Anal fissure (disorder)
• 197151007 Acute anal fissure (disorder)
• 197152000 Chronic anal fissure (disorder)