Anorectal Procedures

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Chapter 45

Anorectal Procedures

Patients with anorectal disorders are frequently encountered in the emergency department (ED). In some cases the condition is isolated, whereas in others, the anorectal complaint may be an outward manifestation of a serious underlying illness. A thorough history and physical examination must precede any procedure. Because of the nature of these conditions, extreme sensitivity and professionalism must be applied.

Patients may be anxious about anorectal examination or associated procedures, including the simple digital rectal examination (DRE). The results of DRE may lead to performing diagnostic or therapeutic procedures, such as anoscopy, excision of thrombosed external hemorrhoids, drainage of anorectal abscesses or pilonidal cysts, reduction of rectal prolapse, or removal of rectal foreign bodies (FBs). For these procedures, analgesia, sedation, or both may be useful adjuncts.

Anatomy

The rectum and anus compose the most distal portion of the gastrointestinal tract. The rectum begins at the level of the third sacral vertebra and extends distally 12 to 15 cm. Blood supply to the anorectum is derived from the superior, middle, and inferior hemorrhoidal arteries. Venous drainage from the rectum and anus returns to both the portal and systemic systems (Fig. 45-1). The dentate or pectinate line marks the transition from the rectum to the anus and contains submucosal glands in anal crypts. Occlusion with subsequent infection of these glands is the etiology of anorectal abscesses. Sensory innervation to the rectum is primarily visceral, whereas the anus is innervated by cutaneous fibers. Therefore, patients are often unaware of rectal pathology because the pain associated with it may be vague or absent. By contrast, anal lesions are usually very painful and well localized.1

DRE

Procedure

The examiner should place the patient in the lateral decubitus position and wear protective gloves. The examination begins with a preliminary visual inspection of the perianal area for important information regarding patient hygiene, trauma, or sexually transmitted diseases. Next, ask the patient to perform a Valsalva maneuver and note any prolapsing rectal mucosa or hemorrhoids. When the patient relaxes, prolapsed structures may retreat or remain external to the anus. By placing a finger firmly against the anal sphincter, it will relax and allow entry of the examiner’s gloved, lubricated finger (Fig. 45-2A). Once inserted into the anus, make a 360-degree sweep to identify any irregularities in the anorectum and prostate. On withdrawal of the examining finger, examine stool remaining on the glove for the presence of visible or occult blood (see Fig. 45-2B and C).2 Testing for blood in stool is discussed in detail in Chapter 67.

Complications

Although DRE causes some vasovagal depression, it is safe to perform in patients with acute myocardial infarction.3 Although not a firm contraindication in patients whose absolute neutrophil count is dangerously low, some would defer routine DRE, especially avoiding vigorous prostate manipulation, to minimize the likelihood of bacteremia.

Anoscopy

Procedure

Although most patients do not require intravenous sedation and analgesia, administer these agents as needed to keep the patient relaxed and comfortable. Before anoscopy, perform a routine DRE to identify sources of bleeding or pain and to locate any palpable masses. After DRE and with the obturator inserted completely into the anoscope, carefully introduce the scope into the anus. Use gentle, constant pressure to overcome resistance from involuntary contraction of the external anal sphincter. Gently advance the anoscope while asking the patient to bear down slightly. Pass the anoscope gently into the anorectum (see Fig. 45-4, step 2). If the obturator falls back during insertion, remove the anoscope completely and replace the obturator to avoid pinching the anal mucosa. Advance the anoscope until the outer flange impinges on the anal verge. Unless the anoscope has an internal light, use an external light source such as a penlight, otoscope, or pelvic examination light.

When the anoscope is fully inserted, remove the obturator (see Fig. 45-4, step 3). While gradually withdrawing the anoscope, visualize the anal canal (see Fig. 45-4, step 4). Swab away blood or debris to aid in visualization, and culture any abnormal discharge that is found. Note whether there is rectal bleeding or an FB beyond the reach of the anoscope. Withdraw the anoscope slowly as the entire circumference of mucosa is inspected for hemorrhoids, anal fissures, ulcerations, abscesses, or tears. Near the last stage of withdrawal, be aware of reflex spasm of the anal sphincter, which may cause the anoscope to be expelled quickly. Use firm counterpressure to prevent such rapid expulsion.

Management of Hemorrhoids

Hemorrhoids are a common affliction and have been described and treated for more than 4000 years. The refined, low-fiber diet of Western nations makes hemorrhoids extremely common in the United States, where 1 in 25 to 30 individuals is afflicted. One million patients annually seek medical attention for this condition.4

Hemorrhoidal tissue is composed of vascular, mucosal, and muscular tissue. Though frequently attributed to varicosities, all three elements are included in hemorrhoids (Fig. 45-5). There are two types of hemorrhoids: internal and external. Internal hemorrhoids originate above the dentate line, are covered with mucosa, and lack sensory innervation. They can be identified by noting that their covering differs in appearance from the surrounding perianal skin. Internal hemorrhoids may prolapse and bleed, which usually produces bright red blood on toilet paper or in the toilet bowel. This bleeding is arterial from presinusoidal arterioles and is mostly associated with brown stool and bleeding only with a bowel movement. Atypical bleeding requires further investigation. Internal hemorrhoids are rarely felt by digital palpation unless they are very large or thrombosed. Internal hemorrhoids are usually painless unless gangrenous, strangulated, extruded, or thrombosed, and then they may be extremely painful. Anal pain in the absence of such pathology suggests a problem other than simple internal hemorrhoids.5

Internal hemorrhoids can be further classified as first through fourth degree. First-degree hemorrhoids do not prolapse but may be identified on anoscopic examination. Second-degree hemorrhoids prolapse on straining but reduce spontaneously. Third-degree hemorrhoids prolapse on straining and can be reduced manually, whereas fourth-degree hemorrhoids prolapse and are irreducible. Fourth-degree hemorrhoids are prone to thrombosis, strangulation, and eventually gangrene (see Fig. 45-5C).

External hemorrhoids originate below the dentate line and are covered with squamous epithelium. This makes them easily recognizable because their covering matches the surrounding skin. A thrombosed external hemorrhoid appears as a bluish mass covered by epidermis. Acute thrombosis occurs suddenly and is generally very painful because external hemorrhoids are innervated by the inferior rectal nerve. Many patients feel a tender mass and are unable to sit comfortably. Significant bleeding is uncommon but may occur with spontaneous rupture. Increased pressure from straining or trauma from constipation or diarrhea may exacerbate external hemorrhoids. Distention and trauma predispose the hemorrhoidal venous plexus to stasis with ensuing clot formation and edema.2,4,69

Conservative Treatment

ED management of minor internal hemorrhoids is conservative. Prolapsing internal hemorrhoids will not benefit long-term from conservative intervention and should receive surgical consultation. A useful mnemonic for managing hemorrhoids is WASH: water (increase fluid intake, warm water contacting the hemorrhoid via bath or directed shower), analgesics, stool softeners, and a high-fiber diet.2 Psyllium (e.g., Metamucil) is often prescribed as a dietary supplement to increase fiber. Hemorrhoids that fail to respond to medical management may be treated on an outpatient basis with rubber band ligation, sclerosis, and thermotherapy consisting of an infrared beam, electric current, CO2

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