Definition, Etiology, PathogenesisTop
An anal fissure is a tear in the epithelial lining of the distal anal canal.
The exact cause of anal fissures is not known. An initiating event, such as passage of a hard stool or trauma, causes a tear in the epithelial lining. High resting anal canal pressure and reduced blood flow prevents healing and results in mucosal ischemia and fissure formation. Some risk factors that may contribute are diets lacking in fiber, previous anal surgery, childbirth, and laxative abuse.
The most common location is the posterior midline (up to 90% of cases). Anterior midline fissures are less frequent and are more common in women than in men. However, the most common location in women are posterior midline fissures. Lateral fissures are the least common.
Atypical fissures that are lateral, nonhealing, or nonsolitary should raise suspicion of diseases such as Crohn disease, tuberculosis, syphilis, human immunodeficiency virus/AIDS, other dermatologic conditions (eg, psoriasis), leukemia, or anal carcinoma.
Clinical Features and Natural HistoryTop
The main symptoms are sharp or burning pain on defecation that can last for hours after defecation and mild rectal bleeding (eg, bright red blood on toilet paper).
The most important physical examination is inspection of the perianal area by gentle effacement of the anus by separation of the buttocks. Chronic fissures (symptoms persisting for more than 6-8 weeks) also have associated features, such as an external sentinel anal tag and hypertrophied anal papilla internally. Digital rectal examination is often deferred due to severe pain and increased anal sphincter tone that makes the examination difficult.
Diagnosis is usually made on the basis of history and physical examination.
Endoscopic examination may be delayed until pain resolution after treatment. Biopsies should be done if the fissure is atypical or nonhealing to exclude other diagnoses.
The goal of treatment is to achieve internal sphincter relaxation to allow healing without fecal incontinence. Special attention should be paid to treatment of atypical fissures, such as in Crohn disease; expert opinion should be sought.
1. Conservative management includes dietary modification for prevention of constipation, fiber supplementation, stool softeners if necessary, and warm sitz baths.
2. Medical treatment involves use of topical medications that produce reversible chemical sphincterotomy as an initial treatment for acute fissures.Evidence 1Strong recommendation (benefits outweigh downsides; right action for all or almost all patients). Moderate Quality of Evidence (moderate confidence that we know true effects of the intervention). Quality of Evidence lowered due to the marginal effect of intervention. Randomized controlled studies demonstrate that medical treatments have marginally better rates of healing than placebo (eg, 49% healing with nitroglycerin vs 36% with placebo). Nelson RL, Thomas K, Morgan J, Jones A. Non surgical therapy for anal fissure. Cochrane Database Syst Rev. 2012 Feb 15;(2):CD003431. doi: 10.1002/14651858.CD003431.pub3. Review. PubMed PMID: 22336789. Topical calcium channel blockers such as diltiazem (2%) or nifedipine ointment may be used. Topical nitroglycerin (0.2 or 0.4%) is another option; however, adverse effects are more common than with calcium channel blockers. Medical treatment has marginally better healing rates than placebo.
3. Botulinum toxin injections into the internal sphincter can be performed in medically refractory chronic fissures.Evidence 2Weak recommendation (benefits likely outweigh downsides, but the balance is close or uncertain; an alternative course of action may be better for some patients). Moderate Quality of Evidence (moderate confidence that we know true effects of the intervention). Quality of Evidence lowered due to significant indirectness and heterogeneity (variability in administration dose, site, and frequency of injections in the studies as well as variability in healing rates reported in studies). Nelson RL, Thomas K, Morgan J, Jones A. Non surgical therapy for anal fissure. Cochrane Database Syst Rev. 2012 Feb 15;(2):CD003431. doi: 10.1002/14651858.CD003431.pub3. Review. PubMed PMID: 22336789. Healing rates are no different from medical treatment but there is significant variability in dose, site, and frequency of injections that may affect the results.
4. Surgical treatment is reserved for severe chronic medically refractory fissures. In this situation, lateral internal sphincterotomy is the treatment of choice with the highest healing rates, although the risk of incontinence exists.Evidence 3Strong recommendation (benefits outweigh downsides; right action for all or almost all patients). High Quality of Evidence (high confidence that we know true effects of the intervention). Nelson RL, Chattopadhyay A, Brooks W, Platt I, Paavana T, Earl S. Operative procedures for fissure in ano. Cochrane Database Syst Rev. 2011 Nov 9;(11):CD002199. doi: 10.1002/14651858.CD002199.pub4. Review. PubMed PMID: 22071803.