Anal fissures

Anal fissures are a longitudinal tear in the anoderm, typically located distal to the dentate line in the posterior midline, and are most commonly caused by increased anal sphincter tone. Fissures are classified by their cause (e.g., trauma, underlying disease) and duration (acute or chronic). Manifestations typically include sharp, severe pain during defecation and bright red rectal bleeding. Diagnosis is clinical, based on history and physical examination, though further evaluation is necessary if the diagnosis is unclear or if there are atypical features. Management is primarily conservative, involving stool softeners, analgesics, topical anesthetics, and topical vasodilators. Surgery, such as lateral internal sphincterotomy, should be considered if conservative management is unsuccessful, but carries a risk of fecal incontinence.

• 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)

• Overdistention 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 distention 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).

• Acute anal fissure ^[1][2]
  • Typically a single superficial tear in the anoderm in the posterior midline
  • Sharp, severe pain during defecation
  • Bright red blood on stool or toilet paper
  • Intermittent postdefecation pain
  • Perianal pruritus
  • Chronic constipation
• Chronic anal fissure ^[1][2]
  • Cyclical sharp, severe pain with defecation ^[3]
  • External skin tags (sentinel pile)
  • Internal hypertrophied anal papillae
  • Exposed internal sphincter muscle fibers

4 D's of anal fissures: Distal to the dentate line, Defecation pain with bleeding, Dull pudendal pain, Diet low in fiber

Anal fissures are a clinical diagnosis (see “Clinical features”). Further diagnostics are required if the diagnosis is unclear or to rule out underlying pathologies, e.g., in patients with chronic fissures. ^[1][2]

• Digital rectal examination
  • Use topical lidocaine ointment before performing the examination and consider examination under sedation.
  • Only performed if the diagnosis is unclear or to rule out other pathologies (e.g., rectal tumor)
• Anoscopy: indicated if the fissure is not easily visualized or has an atypical presentation ^[4]
• Endoscopy ^[2][5]
  • Indicated for unclear diagnosis, red flags for colorectal cancer, and exclusion of IBD
  • Consider delaying until after fissure treatment to reduce discomfort.
• Imaging (e.g., CT scan, MRI, or endoanal ultrasound): only performed if there is suspicion of IBD or anal or colorectal cancer ^[6]

Consider additional diagnostics for atypical (lateral or multiple) or persistent fissures to rule out secondary causes (e.g., Crohn disease). ^[2]

In patients with rectal bleeding and red flags for colorectal cancer, the presence of a fissure should not delay further diagnostics. ^[7]

Proctalgia fugax ^[8][9]

• Definition: a functional disorder characterized by recurring episodes of sudden and sharp pain in the anorectal region unrelated to defecation
• Epidemiology ^[10]
  • 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 ^[11]
  • Reassurance
  • Biofeedback therapy
  • Topical antispasmodics (e.g., nitroglycerin)
  • Inhaled beta-2-adrenergic agonists

Other

• Hemorrhoids
• Perianal ulcer
• Anal fistula or abscess
• Anal carcinoma

The differential diagnoses listed here are not exhaustive.

Acute management ^[1][2][12]

• Lifestyle changes for constipation: increased dietary fiber and water intake
• Pharmacological treatment
  • Nonopioid analgesia
  • Topical calcium channel blockers (e.g., nifedipine, diltiazem) or nitroglycerin
  • Topical anesthetic ointments (e.g., lidocaine gel)
  • Topical hydrocortisone ^[13]
• Supportive management
  • Warm sitz baths
  • Bulk-forming laxatives, stool softeners

Interventional and surgical management ^[1][2][12]

Refer patients with chronic anal fissures to a colorectal surgeon.

• Minimally invasive treatment: botulinum toxin A injection into the internal anal sphincter ^[14]
• Surgery: indicated if conservative management is unsuccessful after 8–12 weeks
  • Lateral internal sphincterotomy: gold standard treatment with a lower risk of fecal incontinence than other surgical options ^[4]
  • Other options: anal dilation, anal advancement flap, fissurectomy

Conservative management is typically effective for acute fissures; surgery is reserved for chronic fissures due to the risk of fecal incontinence.