Anal Fissure

An anal fissure is a painful superficial tear of the epithelial lining (anoderm) of the anal canal. Anal fissures most often occur secondary to local trauma or irritation from constipation, diarrhea, anal intercourse, or perineal lacerations during childbirth. Treatment is generally conservative, including stool softeners, bulking agents, sitz baths, and/or topical vasodilators.

Last update:

Table of Contents

Share this concept:

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on email
Share on whatsapp

Definition and Epidemiology


  • Superficial tear of the epithelial lining (anoderm) of the anal canal 
  • Distal to the dentate line
  • Acute fissures involve the epithelium.
  • Chronic fissures involve the full thickness of the anal mucosa.


  • Most common in infants and middle-aged adults
  • Exact incidence unknown
  • Males and females equally affected

Etiology and Pathophysiology


  • Acute fissure
    • Forceful dilation of the anal canal (local trauma) due to:
      • Large, hard stools secondary to constipation
      • Irritating, diarrheal stools
      • Anal intercourse
    • Other causes:
      • Habitual use of cathartics
      • Childbirth with 3rd- or 4th-degree perineal lacerations
  • Chronic fissure (due to underlying disease)
    • Previous anal surgery (possible stenosis of the anal canal)
    • Crohn’s disease
    • Infections
      • Tuberculosis
      • HIV
      • Chlamydia
      • Syphilis
    • Leukemia
    • Squamous cell anal carcinoma


  • Location: 90% posterior midline, 10% anterior midline 
    • Most posterior midline fissures occur due to:
      • Shearing forces during defecation
      • Decreased elasticity of the anal epithelium
      • Increased density of longitudinal muscle extensions
    • Most anterior midline fissures occur from vaginal delivery
    • If the anal fissure is not midline, consider possible causes such as Crohn’s disease, infections, or anal cancer.
  • Repetitive injury often occurs due to:
    • Local trauma
    • Anal hypertonicity
      • Tightening of the anal canal secondary to pain leads to further tearing.
    • Sphincter spasm
      • Prevents edges from healing and leads to further tearing
    • Vascular insufficiency due to:
      • Increased sphincter tone 
      • Decreased perfusion from large anal canal circumference

Clinical Presentation

  • Acute fissure
    • Symptoms: < 8 weeks
    • History:
      • Severe onset of anal pain with defecation; often lasts for hours afterward
      • Constipation
      • Hematochezia (bright-red blood in stools)
    • Physical exam findings:
      • Sphincter spasm on digital rectal examination (DRE) due to the pain
      • Often appears as a superficial laceration in anal mucosa
  • Chronic fissure
    • Symptoms: lasting > 8 weeks
    • Physical exam findings:
      • Tear in anal mucosa with possible visible fibers of anal sphincter
      • Sentinel skin tags (external skin tags)
      • Hypertrophied anal papillae

Diagnosis and Management


  • History is often classic and the basis of diagnosis.
  • Confirmed on physical examination by:
    • Direct visualization
    • Reproducible anal pain with gentle palpation
  • If fissure is not midline or history is more complicated, then additional testing may be warranted:
    • Anoscopy
    • Biopsy
    • HIV testing
    • Stool cultures


  • Medical management
    • Goals: 
      • Eliminate constipation. 
      • Decrease anal spams.
      • Prevent further anal epithelial tears. 
      • Promote healing.
    • Treatment may include:
      • Stool softeners, bulking agents, sitz baths
      • Topical nitroglycerin or nifedipine: increases local blood flow (vasodilates), promoting healing and relieving sphincter spasm
      • Topical lidocaine
      • Botulinum toxin injections
        • Inhibit the release of acetylcholine (ACh)
        • Reduce sphincter spasm
        • Long lasting (up to 3 months)
  • Surgical management
    • Reserved for fissures refractory to medical management or chronic fissures 
    • Surgical options:
      • Lateral internal anal sphincterotomy 
        • Most effective
        • Current procedure of choice
        • Relieves sphincter spasm → increases blood flow and promotes healing 
        • Can be done with or without fissurectomy
      • Anal advancement flap (anoplasty)
      • Sphincter dilation (no longer commonly used secondary to high complication rates)


The “Ds” of anal fissures: 

  • Distal to the Dental line
  • bleeDing During Defecation; 
  • Dull puDenDal pain
  • Diet low in fiber (constipation)

Differential Diagnosis

  • Anal carcinoma: neoplastic disease in which cancer cells form and grow in the anus. Symptoms include bleeding from the anus, anal pain, anal mass, or itching. Risk factors include older age, infections such as human papillomavirus (HPV), multiple sexual partners, and anal sex. Anal carcinoma is diagnosed by biopsy. Treatment can include surgery, radiation, or chemotherapy. In a chronic or atypical anal fissure, anal carcinoma needs to be ruled out.
  • Anal fistula or abscess: an abnormal connection between the epithelium of the anal canal and another body structure. Anal fistulas often occur due to extension of anal abscesses. Symptoms include anal pain or abnormal discharge/drainage. Management is primarily surgical, with a fistulotomy. Anal abscesses produce a tender bulge/mass in the anorectal region. In anal fistulas, there is the presence of a palpable fistulous tract.
  • Hemorrhoids: enlargement of anal cushions (submucosal vessels) at the distal rectum. Depending on the location of the veins, hemorrhoids can be internal or external. External hemorrhoids are painful, whereas internal hemorrhoids are painless; both can bleed and appear as a soft rectal mass on exam. Commonly caused by constipation, and diagnosed on exam. Treatment includes stool softeners, topical hydrocortisone, and sitz baths. Additional treatment options are rubber band ligation or surgical removal.  
  • Perianal ulcerations: erosions in the perianal mucosa. Occur secondary to inflammatory bowel disease, most notably Crohn’s disease, infections, and cancer. Symptoms include pain, bleeding, and erosions in the lining of the mucosa. Treatment is aimed at the causative disease. Perianal ulcerations are differentiated from anal fissures on physical exam by deeper erosions in mucosa and evidence of other causative diseases.


  1. Poritz, Lisa A. (2020). Anal Fissure Treatment & Management. Medscape. Retrieved Oct 2, 2020, from
  2. Stewart, David B. (2020). Anal fissure: Clinical manifestations, diagnosis, prevention. Uptodate. Retrieved Oct 1st, 2020, from

Study on the Go

Lecturio Medical complements your studies with evidence-based learning strategies, video lectures, quiz questions, and more – all combined in one easy-to-use resource.

Learn even more with Lecturio:

Complement your med school studies with Lecturio’s all-in-one study companion, delivered with evidence-based learning strategies.

🍪 Lecturio is using cookies to improve your user experience. By continuing use of our service you agree upon our Data Privacy Statement.