Anal Fissure

Background

• Anal fissure is a linear split or tear in the skin of the distal anal canal, extending below the dentate line to the anal verge.
  • Primary anal fissures are idiopathic in that they are not caused by an underlying chronic disease; precipitating factors are thought to include:
    • trauma caused by the passage of large or hard stools (constipation)
    • diarrhea
    • internal sphincter hypertonia
    • trauma during vaginal delivery
  • Secondary anal fissures develop secondary to an underlying chronic disease, such as:
    • chronic inflammatory bowel disease (such as Crohn disease or ulcerative colitis)
    • syphilis
    • tuberculosis
    • leukemia or carcinoma
    • herpes genitalis
    • cytomegalovirus infection
    • chlamydia genital infection
    • Haemophilus ducreyi
    • HIV infection
    • psoriasis or other dermatologic conditions
• Anal fissures are common but the exact incidence is unknown.
  • There is an 11% estimated lifetime incidence.
  • They are reported to be the most common cause of rectal bleeding in infants.
• Spontaneous healing (with the aid of conservative measures to control pain) is reported in:
  • most patients with acute anal fissures
  • about 40% of patients with chronic anal fissures

Evaluation

• Suspect the diagnosis in patients reporting intense anal pain, often with bleeding, during and after defecation.
• A rectal exam with gentle separation of the buttocks can visually confirm a fissure, but may be limited by patient pain and discomfort.
  • An acute fissure may present with a simple tear in the anoderm.
  • Chronic fissures may present with:
    • edema
    • fibrosis
    • an indurated ulcer with exposed white fibers of the internal anal sphincter visible at the fissure base
    • a sentinel skin tag (a small external lump), which indicates a likely fissure even if the fissure is not readily visible
    • a hypertrophied anal papilla in the anal canal proximal to the fissure
• Additional testing, including examination under anesthesia with anoscopy, endoscopy, biopsy, and imaging (such as computed tomography [CT] scan, magnetic resonance imaging [MRI], or endoanal ultrasound) may be necessary in patients with:
  • a fissure that is not visible on exam
  • unclear diagnosis
  • significant bright red bleeding in a patient who is at increased risk for colorectal cancer
  • features suggesting a secondary anal fissure (including lateral or multiple fissures, or a fissure that does not resolve with treatment)

Management

• Initiate nonoperative treatment for the initial management in most patients with anal fissures (Strong recommendation).
  • Advise a high-fiber diet (or dietary fiber supplementation) and adequate fluid intake to reduce constipation and straining during defecation.
  • Other conservative treatments to help control symptoms include:
    • bulk-forming laxatives
    • warm sitz baths
    • topical lidocaine 2% or 5% cream
    • topical steroids, such as hydrocortisone 1% cream, to reduce inflammation
  • Topical medications for use in patients with anal fissures include:
    • topical nitrate treatment (Strong recommendation)
    • topical calcium channel blockers (reported to have fewer adverse side effects than topical nitrates) (Strong recommendation)
  • For chronic anal fissures refractory to conservative treatment and topical medications, administer botulin toxin injections into the internal anal sphincter (Strong recommendation).
• For patients refractory to nonoperative treatment:
  • Lateral internal sphincterotomy (LIS) is recommended as the surgical treatment of choice (Strong recommendation).
    • LIS open and closed procedures are reported to have similar results.
    • Tailoring LIS to anal fissure characteristics (a "tailored sphincterotomy") is reported to have less incontinence and equivalent or worse healing than traditional LIS that reaches the dentate line.
  • Subcutaneous fissurectomy and anal advancement flap surgery are sphincter-sparing alternatives to sphincterotomy in patients with chronic anal fissures (Weak recommendation).
    • Fissurectomy can also be performed in addition to other procedures, including:
      • botulinum toxin injection (combination treatment reported to improve healing while avoiding the risk of sphincterotomy)
      • sphincterotomy (less commonly performed due to the potential for a keyhole deformity with mucus leakage, which is reported in up to one-third of patients)
• Although nonoperative treatment for the initial management in most patients with anal fissures is recommended, surgery may be performed without a prior medical treatment failure (Weak recommendation).
  • Surgical treatment consistently yields superior results compared to medical therapy.
  • Compliance with medical therapy may be an issue in the long term.