Introduction
An anal fissure, although ostensibly a minor problem, may lead to years of tremendous discomfort if not promptly diagnosed. Too often, the problem remains underrated or unnoticed by clinicians. However, when considered, the diagnosis is rather simple to make, and the treatment is usually quite effective.
For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles, Anal Abscess, Abdominal Pain in Children, and Rectal Bleeding.
Problem
An anal fissure is a tear of the squamous epithelial mucosa of the anal canal, between the anocutaneous junction and the dentate line. They most commonly occur during passage of a firm stool. Anal fissures are common in infancy, and they represent the most common cause of bright rectal bleeding at any age. If not promptly diagnosed and treated, these small tears and their occasionally associated superficial infection cause severe anorectal pain during bowel movements and set in motion a cycle of stool negativism, constipation, and increasing pain with subsequent defecation.
Frequency
Most fissures affecting the pediatric population manifest in children aged 6-24 months; however, the overall incidence of the problem is not well described.
Etiology
The generally accepted proximal cause of the anal fissure is a mechanical tear resulting from the passage of hard stool. An unhealed fissure may become infected and develop into a chronic ulcer. A healed fissure may develop into a classic sentinel skin tag in the posterior midline.
The differential diagnosis includes pruritus ani, inflammatory bowel disease, tuberculosis, inherited disorders of the immune system, acquired immunodeficiency syndrome (AIDS), chlamydia, gonorrhea, syphilis, or neoplasm. Also, sexual abuse should always be considered in the differential when evaluating patients with anal or genital complaints. Most anal fissures are single in number and occur at the posterior midline. Multiple fissures of the anal canal, lateral fissures, or those that extend proximal to the dentate line should raise the suspicion of a more serious underlying disease process. Lateral fissures should raise the possibility of trauma, infection, neoplasm, AIDS, syphilis, tuberculosis, or inflammatory bowel disease.
Pathophysiology
The underlying pathophysiology of anal fissures is fairly complex. It is likely to be multifactorial and may involve anodermal ischemia, infection, chronic constipation, and hypertonicity of the smooth muscle of the internal anal sphincter and its elevated resting pressure.Fissures have a predilection for the posterior midline (90%) but may also be located in the anterior midline or lateral. The explanation for this phenomenon is both anatomic and functional. The posterior commissure of the anoderm is less well perfused than other anodermal regions. Furthermore, before the branches of the inferior rectal artery reach the anoderm, they course perpendicularly through septa of the internal anal sphincter. Thus, flow through these arterioles is threatened by elevated intramuscular pressure of the internal anal sphincter.
Many studies have demonstrated that adult patients with anal fissures have significantly elevated anal canal pressures that exceed the intraluminal pressure of arterioles. Therefore, increased tone at the internal anal sphincter compromises perfusion of the anoderm, particularly at the posterior midline, by compressing arterioles of the inferior rectal artery. High canal pressures likely result in increased anodermal ischemia that prevents small mechanical tears from healing in a timely fashion; the tears then progress to clinically significant anal fissures. A similar pathophysiology is speculated to be the etiology of anal fissures in infants and children.
Presentation
The diagnosis is usually made through a careful history and physical examination. A history of constipation is often elicited. The child may cry with bowel movements, and streaks of bright red blood on the surface of hard stool, on the diaper, or on the toilet paper after a bowel movement may be identified by the patient or family. Remember that underlying systemic illness frequently manifests with anal lesions. Thus, pertinent negatives, such as fever, rash, oral or skin lesions, weight loss, diarrhea, and abdominal pain, should be excluded. Also, psychological problems and stressors that may provoke stool negativism should be elicited.
The diagnosis is established by inspecting the anal region. For this examination, the parents should hold the child's hips in acute flexion while the examiner separates the buttocks, retracting the perianal skin folds. For older children, the anoderm may be spread apart while the child bears down because this maneuver facilitates visualizing the fissure. If a fissure is identified, a digital examination is best avoided because it is likely to elicit unnecessary pain and sphincter spasm. However, if a fissure is not observed, a digital examination should be performed to rule out other pathology. If the examination is limited by pain and the diagnosis remains unclear, an examination under anesthesia should be pursued.
The fissure appears as a minor laceration, usually in the midline, and is more often posterior than anterior. If the fissure is chronic, a small external skin tag (ie, sentinel tag) may be identified at the base of the laceration; this represents epithelialized granulomatous tissue secondary to chronic inflammation.
If a fissure is suspected, palpation of the abdomen is essential to check for palpable masses (stool) in the left lower quadrant.
Indications
Acute fissures rarely require surgical intervention, and symptoms from an acute fissure often resolve within 10-14 days of conservative medical management. However, if an anal fissure does not heal after 6-8 weeks of medical therapy and the diagnosis is not in question, surgery may be indicated.
Relevant Anatomy
See Pathophysiology.
Contraindications
Relative contraindications to operative treatment of anal fissure include inflammatory bowel disease and profound immunosuppression (ie, absolute neutrophil counts <100/μL).
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References
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Further Reading
Keywords
anal fissure, fissure in ano, anal tear, tear of the squamous epithelial mucosa of the anal canal, tear of the anal canal, bright rectal bleeding, posterior midline tear, constipation, anorectal pain, passage of hard stool, blood in the stool, anorectal blood, rectal blood, rectal bleeding, anal skin tag, chronic ulcer, acquired immunodeficiency syndrome, chlamydia, gonorrhea, syphilis, neoplasm, sexual abuse, inflammatory bowel disease
