Anorectal Procedures

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Chapter 45

Anorectal Procedures

Wendy C. Coates

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

Figure 45-1 Anatomy of the terminal gastrointestinal tract. (Redrawn from Abrahams PH, Webb PJ. Clinical Anatomy of Practical Procedures. London: Pitman; 1975.)

DRE

Indications and Contraindications

The physical examination should be performed in a private location and the patient should be completely draped and relaxed. Generally, a calm atmosphere and caring examiner preclude the need for analgesic or anxiolytic agents, although they may be needed to facilitate a thorough examination. In some extremely painful conditions, such as thrombosed or gangrenous hemorrhoids, DRE may be postponed until the patient is anesthetized. If a sharp-edged foreign body (e.g., metal blade or broken glass) is suspected, performing a DRE may cause injury to the clinician, as well as the patient. In these cases, radiologic evaluation with subsequent operative management may be indicated.

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.

Figure 45-2 Digital rectal examination. A, Insert a gloved, lubricated finger into the anus and perform a 360-degree sweep to check for any irregularities in the anorectum and prostate. B, Examine the stool for visible and occult blood. This patient had melena, which is very dark and tarry in consistency and indicative of upper gastrointestinal hemorrhage. C, This sample is positive for blood. The large arrow points to the blue coloration on the test area of the card, whereas the small arrow points to the control.

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

Indications and Contraindications

When evaluating a patient for anal pathology, some practitioners use anoscopy as an adjunct to DRE. Internal hemorrhoids, tears in the distal rectal mucosa, FBs, and distal anorectal masses may be visualized. An imperforate anus is the only absolute contraindication to anoscopy; however, severe rectal pain, a common complaint in the ED, may preclude awake anoscopic examination in anxious patients or those suffering from thrombosed hemorrhoids or other painful conditions. Internal visual inspection in these patients is better performed with sedation. In many cases a more definitive study such as sigmoidoscopy or colonoscopy is being planned by the treating physician, and thus anoscopy can be deferred in the acute care setting.

Equipment and Setup

The anoscope is a plastic or stainless steel tube with a removable obturator (Fig. 45-3). It may have an integrated light source or require an external light or head lamp. An appropriate examination table, topical anesthetics, lubricant, gauze, and forceps may also be required.

Figure 45-3 Reusable stainless steel (A) and disposable plastic (B) anoscopes are available. Regardless of the type of anoscope used, the obturator must be fully inserted and held in place with the thumb during advancement of the device into the anorectum.

Positioning

Ideally, place the patient in a prone position on a proctoscopic examination table. The prone or lateral decubitus position with the knees and hips flexed may also be adequate and is sometimes tolerated better. In the lateral decubitus position, place the patient on the left side if the examiner is right-handed (Fig. 45-4, step 1).

Figure 45-4 Anoscopy. Remember to keep your thumb on the obturator during passage of the instrument until it is fully inserted. (Step 1, From Hill GJ II. Outpatient Surgery. 3rd ed. Philadelphia: Saunders; 1988.)

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.

Complications

Although complications are rare, patients often complain of increased pain after the examination. Local mucosal irritation with subsequent bleeding is the most common complication. To prevent transmission of infectious diseases, dispose of or sterilize instruments after each use.

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