Fissure-in-Ano - Clinical Tree

Anal fissure (fissure-in-ano) is a common condition that usually presents as anal pain or bleeding with defecation. It is easily confused with symptomatic hemorrhoids. It can be very troubling because the severity of patient discomfort and extent of disability far exceed that which would be expected from such trivial lesion.

Bleeding is a common symptom and is usually scant, bright red, and found on the tissue when cleansing after a bowel movement. Anal fissure is described as a linear defect, or laceration, in the anoderm, located between the dentate line and the anal verge. It can be acute or chronic. An acute fissure is a simple laceration, whereas a chronic anal fissure is an ulceration with built-up scarred edges and exposed internal anal sphincter muscle fibers at its base. Additional findings may include a perianal skin tag at the external margin of the fissure and a hypertrophied papilla at the dentate line. Chronic fissure is defined by these three findings—visible muscle, a skin tag (sentinel tag), and hypertrophied papilla ( Fig. 159.1 ). Importantly, acute and chronic anal fissures are almost always located in the midline, with the posterior location predominating. However, in 10% of women and in 1% of men, anal fissure can be seen in the anterior midline. Fissures located off the midline are usually associated with more serious systemic diseases such as Crohn disease and immunodeficiency syndromes ( Fig. 159.2 ).

Etiology

Trauma to the anal canal, because of passing hard stools, is probably the most frequent cause of fissure-in-ano. Patients will often remember the exact time the fissure developed based on the symptoms. Classically, this will almost always be associated with an episode of constipation. Anal fissure can also be a consequence of frequent defecation and diarrhea. Preexisting anal canal irritation has been postulated to lead to fissure. Scarring, stricture, and stenosis, from prior anal injury or surgery, are recognized conditions that predispose to fissure formation. Because fissures occur most often in the posterior midline, various structural theories have been proposed as causes, the most compelling of which is the vascular anatomy of the internal sphincter.

In 1989 Klosterhalfen et al. reported on anatomic dissections that detailed the blood supply of the inferior hemorrhoidal artery. In the majority of cadaver specimens (85%), the posterior commissure of the anal canal was not directly perfused except by end arterioles. Branching from the sphincteric arterioles occurred at right angles to the parent vessels and coursed perpendicularly through the circular fibers of the internal sphincter. These anatomic findings established the possibility of decreased mucosal perfusion, particularly in the posterior midline. Others have confirmed in cadaveric studies that there is a significant trend to an increasing number of arterioles posterior to anterior in the subanodermal space at all levels. Furthermore, sphincter spasm and hypertonicity, which is common in this disease, may further decrease blood flow posteriorly. Schouten et al. have shown increased anal canal pressures correlated with decreased mucosal blood flow, as measured by laser Doppler flowmetry. Reports of normal anal maximal resting pressure are highly variable, ranging from 60 to 100 cm H ₂ O in females and slightly higher in males; however, the measurement is defined as the maximal pressure recorded at rest. The higher pressures seen in patients with anal fissures will produce a sawtooth pattern on manometry tracings. This vascular-anal hypertonic resting pressure hypothesis has prompted trials aimed at improving blood flow and lowering anal canal resting pressures. Whether sphincter hypertonia is a cause or effect is unknown.

The most common systemic conditions that are associated with atypical anal fissure/anal ulcer are Crohn disease and acquired immunodeficiency syndrome. Both of these conditions lead to an immunocompromised patient. Atypical features include fissures off the true midline, shaggy large defects with undermined edges, and granulation tissue in the base. Actual cavitation of the internal sphincter is another ominous clue to the presence of systemic disease. In the immunocompromised patient, a fissure or an ulcer and a concomitant mass should raise the question of malignancy. Lymphoma, leukemic ulcer, and anal canal epithelial tumors are often associated with surface defects. There are subtle changes, which distinguish these conditions from uncomplicated acute or chronic anal fissure.

Infections also cause fissure-in-ano. Syphilis and tuberculosis were seen frequently in the United States over the last century but are currently uncommon causes of anal fissure. Today, sexually transmitted diseases and infections associated with immunocompromised conditions may be the cause of anal fissure and include chancroid, herpes simplex virus, and cytomegalovirus. Herpes simplex infection manifests as multiple superficial ulcers and vesicles, while syphilitic ulcers are purulent and have a granular base. The treatments for these disease processes are different, and therefore it is important to recognize the differences between anal canal fissures and atypical anal canal ulcers (see Fig. 159.2 ).

Diagnosis

A tearing or burning discomfort during defecation is by far the most common symptom of anal fissure. Bleeding is usually only detected on the toilet paper. The pain associated with anal fissure lasts for minutes to hours, and in patients with acute anal fissure, it is most often described as a cutting or tearing sensation during the act of defecation. The patient often relates that constipation is the antecedent event, but once pain develops, the fear of the act of defecation and refusal of the call to stool can exacerbate this problem. This anxiety leads to fecal impaction, particularly in children and the elderly. Those individuals with a chronic anal fissure will present with a different symptom complex. They may complain of a lump representing the sentinel tag, drainage or discharge from the open wound, pruritus, or a combination of several symptoms. Bleeding may be absent, and pain is usually mild or absent as well. The pain of anal fissure can be differentiated from that of proctalgia fugax in that the latter produces discomfort, which is usually not related to bowel action. In addition, the patient with a fissure feels the discomfort in the anal area, the pain of proctalgia fugaxis higher in the rectum or deep pelvis and more deep-seated. Another anal condition that commonly produces pain is a thrombosed hemorrhoid. With this complaint, the patient also reports feeling a lump, which will not be present if an acute anal fissure is the cause of the pain.

Examination must be carefully performed; the pain caused by an aggressive examination of an anal fissure is not easily forgotten by the patient or examiner. Simple spreading of the buttocks to gently roll open the anal verge will usually demonstrate the fissure ( Fig. 159.3 ). Endoscopy, which must be performed as part of the complete evaluation of patients with fissure, should be postponed; a more complete anorectal examination can be better accomplished when the fissure is healed. Importantly, topical anesthetics do not facilitate pain-free examinations.

Atypical-appearing fissures require more intensive inquiry. Symptoms of inflammatory bowel disease should be sought. Sexual activity and drug history should likewise be documented. If there is cause for concern as to the true nature of the ulcer or fissure, biopsy, stool culture, serology, and gastrointestinal evaluation may be indicated. High-risk behavior for human immunodeficiency virus infection necessitates screening and may explain the presence of the atypical fissure. Syphilitic ulcers can be diagnosed with dark-field, wet prep microscopy. Tuberculous ulcer, although commonly superinfected, will show acid-fast bacilli on staining. The critical issue in patients with atypical-appearing fissures is a high index of suspicion. If an atypical fissure is treated the same way as a typical fissure, a large nonhealing wound could result.

Most diagnostic tests will not be tolerated as office procedures. Examination under anesthesia permits a thorough evaluation of the anus and rectum. Cultures, biopsies, and possible therapeutic interventions can be safely and carefully performed with anesthesia. Indeed, patients embrace the opportunity to have a pain-free evaluation under anesthesia.

Nonsurgical Management

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here