Practice Essentials
An anal fissure is a tear of the squamous epithelial mucosa of the anal canal, between the anocutaneous junction and the dentate line. [1] 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.
An anal fissure, though ostensibly a minor problem, may lead to years of discomfort if diagnosis and treatment are not carried out in a timely fashion. If these small tears (and the occasionally associated superficial infection) are not promptly diagnosed and treated, they can cause severe anorectal pain during bowel movements and set in motion a cycle of stool negativism, constipation, and increasing pain with subsequent defecation.
Too often, this seemingly minor problem remains underappreciated or unnoticed by clinicians. However, the diagnosis, when considered, is rather simple to make, and the treatment is usually quite effective.
The diagnosis is usually made through a careful history and physical examination. (See Presentation.) Laboratory and imaging studies are not routinely necessary in the workup; however, if the presence of an underlying disease process is suspected, additional tests are indicated, such as serology, purified protein derivative of tuberculin (PPD), stool cultures, biopsy, or further gastrointestinal (GI) workup. (See Workup.) An abdominal flat radiograph to check for constipation is often illustrative.
Conservative management is commonly recommended as the first-choice approach for pediatric patients. [2] (See Treatment.) Surgical intervention is rarely required for acute fissures in children, [3, 4] 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.
Patients and their families should be educated about potential urinary retention, severe perianal pain, sepsis, bleeding, and transient fecal incontinence.
Pathophysiology
The underlying pathophysiology of anal fissures is fairly complex. It is likely to be multifactorial and may involve anodermal ischemia, infection, chronic constipation, [5] 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 laterally. 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.
Etiology
The generally accepted proximate 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.
Epidemiology
Most fissures affecting the pediatric population manifest in children aged 6-24 months; however, the overall incidence of the problem has not been well described.
Prognosis
In several small studies, chemical sphincterotomy using glyceryl trinitrate (GTN; ie, nitroglycerin [NTG]) with adjunctive stool softeners was shown to be quite effective at relieving symptoms and promoting healing.
Most pediatric surgeons have reported equal success with open or closed lateral sphincterotomy for acute and chronic anal fissures. [6] Reported recurrence rates for open or closed lateral sphincterotomy have been in the range of 0-10%, with most of the recurrences observed in adults and patients with chronic fissures.
Although most reports have found that anal dilatation and lateral subcutaneous sphincterotomy are both effective therapeutic interventions for chronic anal fissures, anal dilatation has a high recurrence rate (up to 30-40%). Accordingly, it is not recommended in children and has largely been abandoned.
Large prospective series describing outcome in patients following surgical intervention for chronic anal fissure have been lacking in the literature.
