7.1.1 Anal Fissure

Grading & Level of Importance: B


W. Burgdorf, Munich; J. McGrath, London
Revised by A. Salava, E. Hiltunen-Back, A. Ranki, Helsinki




Fissure of the anus.


Most frequent cause of acute anal pain in Europe; incidence peak is in young adults. Annual incidence in Europe is 0.11 % (1.1 cases per 1000 person-years); due to unreported cases, the true incidence is probably much higher.


Painful linear tear in the distal anal canal.

Aetiology & Pathogenesis

The exact etiology of anal fissures is unknown, but usually the initiating factor is a trauma caused by hard or forceful defecation. Obesity, low fiber diets, hypothyroidism, anal tumors and chronic constipation have been associated with the development of anal fissures. Anal fissures may infrequently be associated with Crohn’s disease, HIV infection, artefacts by manipulation and tuberculosis.

Signs & Symptoms

The typical symptom is acutely occurring lacerating pain during bowel movements. Mostly the pain recurs with every defecation, which may lead to a cycle of worsening constipation, harder stools, and increase of anal pain and discomfort (vicious cycle). Many patients note bright-red blood on the toilet paper or stool. Small amounts of blood may be visible in the toilet bowl, but unlike hemorrhoids, significant bleeding does not usually occur. Thus, anal fissures do not cause anemia. Symptoms are relatively specific, and the diagnosis can often be made on patient history alone.


Idiopathic anal fissures are usually localized dorsal in the middle line. If fissures are detected in other localizations, an underlying pathology (e.g. Crohn’s disease) should be excluded.


Most frequently anal fissures resolve spontaneously. After a duration of 6-8 weeks the anal fissure is regarded as chronic.


Sub-mucous abscess, which impedes wound healing; fistulas of the skin or mucosa surface. More rare complications: anal thrombosis, ulceration and incontinence.


The diagnosis is clinical, based on the typical findings of inspection. Proctoscopic rectal examination is painful and often not necessary. If the anal fissure is not visible, the tender wound base of the fissure may be recognizable by gently exploring with the fingertip.

If symptoms are typical and if the fissure is located in the posterior or anterior midline (idiopathic anal fissure), no further tests (biopsy and endoscopy) are necessary.

If fissures are located off the midline, if there are multiple fissures or if an underlying illness is conceivable (notably Crohn’s disease, anal squamous cell cancer, relapsing herpes infection or HIV infection), appropriate tests such as microbiologic swabs, systemic inflammatory parameters, fecal calprotectin, HIV testing and biopsy should be performed.

Differential diagnosis

Relevant differential diagnoses include perianal abscess (pain and palpable fluctuation), perianal fistulas of different origin (secret and/or pus draining) and thrombosed hemorrhoids.

Prevention & Therapy

First-line medical therapy includes stool-bulking agents, such as fiber supplementation and stool softeners. Laxatives should be used as needed to maintain regular bowel movements and treat underlying constipation. 


Second-line therapy consists of topical medicaments that decrease the muscle tonus of the inner anal sphincter. Nitroglycerin applied in different formulations directly to the internal anal sphincter (e.g. nitroglycerin 0,4 % ointment or anal suppositories). Comparable to the use of nitroglycerin ointment, nifedipine ointment is also available in some European countries. The topical treatment should be continued even after the symptoms subside (e.g. 2 months).

In addition to topical treatments, botulinum toxin has been used to treat acute and chronic anal fissures, but poses a small risk of injection site infections. The effect lasts some months, until the regeneration of free nerve endings.


If the anal fissure in unresponsive to conservative treatment and lasts over 2 months surgical intervention should be evaluated. Symptomatic chronic fissures should be treated operatively because they only rarely heal spontaneously.

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