Anal fissures

An anal fissure is a longitudinal tear of the perianal skin distal to the dentate line, often due to increased anal sphincter tone. Anal fissures are classified according to etiology (e.g., trauma or underlying disease) or duration of disease (e.g., acute or chronic). They are typically very painful and may present with bright red blood per rectum (hematochezia). Anal fissures are a clinical diagnosis based on history and examination findings. Management is primarily conservative, and includes stool softeners, analgesia, and possible local muscle relaxation; because of the risk of incontinence, surgical intervention is a last resort.

• Longitudinal tear of the anal canal; distal to the dentate line

Primary (due to local trauma)

• Location: : 90% of all anal fissures located at the posterior commissure (6 o'clock in the lithotomy position)
• Potential causes of trauma:
  • Chronic spasm/increased tone in the internal anal sphincter
  • Low fiber intake
  • Chronic constipation or diarrhea
  • Anal sex
  • Vaginal delivery

Secondary (due to underlying disease)

• Location: may occur lateral or anterior to the posterior commissure
• Underlying conditions:
  • Previous anal surgery (e.g., possible stenosis of anal canal)
  • Inflammatory bowel disease (IBD; e.g., Crohn disease)
  • Granulomatous disease (e.g., tuberculosis)
  • Infections (e.g., chlamydia, HIV)
  • Malignancy (e.g., leukemia)

• Overdistension or disease of the anal mucosa → laceration of the anoderm
  • Spasm of the exposed internal anal sphincter leads to pulling along the laceration, which impairs healing and worsens the extent of laceration with each bowel movement.
  • The resultant pain results in voluntary avoidance of defecation and constipation, which worsens distension of the anal mucosa.
• The posterior commissure is believed to have a very poor blood supply, which predisposes it to ischemia (exacerbated by poor perfusion during increased anal pressure).

References:^[1]

• Sharp, severe pain during defecation
• Rectal bleeding (often bright red and minimal; should not be confused with other types of bleeding such as in colorectal cancer or hemorrhoids)
• Perianal pruritus
• Chronic constipation (see “Pathophysiology” above)

The rule of anal fissure D's: Distally to the Dentate line; bleeDing During Defecation; Dull puDenDal pain; Diet low in fiber

References:^[1][2]

• Clinical examination
  • Superficial or deep laceration in anterior, lateral, or posterior anal canal
  • In addition, chronic fissures may present with fibrotic and infective changes:
    • Wide, raised edges
    • Skin tags (sentinel pile) at the fissure's distal end
    • Hypertrophied anal papillae at the fissure's proximal end
• Clinical history: see “Etiology” and “Clinical features” above
• Digital rectal examination: if diagnosis is uncertain or to exclude a suspected underlying pathology (e.g., rectal tumor)
• Anoscopy
  • Indicated if clinical findings are unclear or if symptoms persist despite adequate treatment
  • Possible biopsy and histological investigation (to exclude a carcinoma, especially when presentation is atypical)

References:^[1]

• Hemorrhoids
• Perianal ulcer
• Anal fistula or abscess
• Anal carcinoma
• Proctalgia fugax ^[3][4]
  • Definition: a functional disorder characterized by recurring episodes of sudden and sharp pain in the anorectal region unrelated to defecation
  • Epidemiology ^[5]
    • Prevalence: 8–18%
    • Sex: ♀ > ♂ (3:2)
    • Age of onset: 30–60 years
  • Precipitating factors
    • Sexual intercourse
    • Prolonged awkward posture or sitting
    • Stress
    • Constipation
    • Menstruation
  • Clinical features
    • Recurring episodes of anorectal pain
    • Pain lasts from seconds to minutes (max. 30 minutes).
    • Pain-free intervals between attacks
  • Diagnostics: a diagnosis of exclusion
  • Treatment ^[6]
    • Reassurance
    • Biofeedback therapy
    • Topical antispasmodics (e.g., nitroglycerin)
    • Inhaled beta-2-adrenergic agonists

The differential diagnoses listed here are not exhaustive.

Conservative

• First‑line treatment for most anal fissures
• Includes:
  • Dietary improvement (e.g., adequate ingestion of dietary fiber and water)
  • Stool softeners (e.g., docusate)
  • Anti‑inflammatory and analgesic creams and/or suppositories (e.g., 2% lidocaine jelly)
  • Sitz baths
  • Local anesthetic injection
  • Topical vasodilator therapy: calcium channel blocker gel (e.g., nifedipine) or glyceryl trinitrate ointment (GTN)

Interim

• Persistent symptoms despite > 8 weeks of conservative therapy → endoscopy to exclude IBD
• If IBD is excluded, then the patient should receive definitive surgical treatment.

Outpatient procedures

• Botulinum toxin A (BTX) injection into the internal anal sphincter

Surgical

• Indicated when conservative treatment is unsuccessful
• The risk of fecal incontinence (e.g., high in multiparous or elderly patients) determines the type of surgical intervention.
  • Low risk
    • Sphincterotomy (e.g., lateral internal sphincterotomy)
    • Anal dilatation (although there is a high risk of fecal incontinence with this procedure)
  • High risk
    • Anal advancement flap
    • Fissurectomy (excision of the fissure)

Conservative therapy is preferred because of the risk of incontinence!
References:^[7][8]