Perianal abscess肛周膿腫.doc

Perianal abscess: Clinical manifestations, diagnosis, treatmentAuthorsElizabeth Breen, MDRonald Bleday, MDSection EditorsMartin Weiser, MDLawrence S Friedman, MDDeputy EditorKathryn A Collins, MD, PhD, FACSDisclosures:Elizabeth Breen, MDNothing to disclose.Ronald Bleday, MDNothing to disclose.Martin Weiser, MDNothing to disclose.Lawrence S Friedman, MDNothing to disclose.Kathryn A Collins, MD, PhD, FACSEmployee of UpToDate, Inc.Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence.Conflict of interest policyAll topics are updated as new evidence becomes available and ourpeer review processis complete.Literature review current through:Nov 2014.|This topic last updated:Sep 18, 2014.INTRODUCTIONA perianal abscess, a simple anorectal abscess, is the acute phase manifestation of a collection of purulent material that arises from glandular crypts in the anus or rectum. In comparison, a perianal fistula represents the chronic phase of suppuration in this perirectal process 1. Perianal abscesses traverse distally in the intersphincteric groove into the perianal skin, where they present as a tender, fluctuant mass (picture 1). A perianal abscess, if undrained, can expand into adjacent tissues (eg, ischiorectal space, supralevator space) as well as progress to a generalized systemic infection.The anatomy of the anal canal and ischiorectal fossa, clinical manifestations, and treatment of an anorectal fistula are reviewed separately. (SeeOperative management of anorectal fistulasandAnorectal fistula: Clinical manifestations, diagnosis, and management principles.)EPIDEMIOLOGYBenign perianal diseases, including fissures, abscesses, fistulas, and hemorrhoids, are common. The prevalence of specific disorders is difficult to estimate since almost any anorectal discomfort is often attributed to symptomatic hemorrhoids.The prevalence of anal abscesses in the general population is probably much higher than seen in clinical practice since the majority of patients with symptoms referable to the anorectum do not seek medical attention. It is estimated that there are approximately 100,000 cases per year in the United States 1. The mean age for presentation of anal abscess and fistula disease is 40 years (range 20 to 60) 2-5. Adult males are twice as likely to develop an abscessand/orfistula compared with women 1,5.PATHOGENESISAn anal abscess usually originates from an infected anal crypt gland 6. There are typically 8 to 10 anal crypt glands, arranged circumferentially within the anal canal at the level of the dentate line. The glands penetrate the internal sphincter and end in the intersphincteric plane. An anal abscess develops when an anal crypt gland becomes obstructed with inspissated debris, which permits bacterial growth and abscess formation. The suppuration follows the path of least resistance and the infected fluid collects in the space where the gland terminates. An anal fistula is a connection between two epithelial structures and connects the anal abscess from the infected anal crypt glands to the skin of the buttocks. There is no model to predict when an abscess will develop a fistula 7.The anatomy of the anal region is described elsewhere (figure 1andfigure 2). (SeeOperative management of anorectal fistulas, section on Anatomy of the anal region.)CLINICAL FEATURESClinical manifestationsPatients with a perianal abscess often present with severe pain in the anal or rectal area. The pain is constant and not necessarily associated with a bowel movement. Constitutional symptoms such as fever and malaise are common. Purulent rectal drainage may be noted if the abscess has begun to drain spontaneously 1.On physical examination, an area of fluctuance or a patch of erythematous, indurated skin overlying the perianal skin may be noted. However, in some patients and with some types of abscesses (eg, supralevator) there are no findings on physical inspection, and the abscess can only be felt via digital rectal examination.Clinical courseApproximately half of anal abscesses will result in the development of a chronic fistula from the inciting anal gland to the skin overlying the drainage site. The risk of developing a fistula is not influenced by whether the fistula drained spontaneously or whether surgical drainage was performed. (SeeAnorectal fistula: Clinical manifestations, diagnosis, and management principles.)DIAGNOSISThe diagnosis of a perianal abscess is based upon the findings from the history and physical examination and includes anorectal pain, fever, and a palpable perirectal mass.Imaging studiesImaging studies, such as computed tomography (CT) or magnetic resonance imaging (MRI), are helpful in the setting of a clinical suspicion of nonpalpable anorectal abscess. The role of imaging tests in the evaluation of anal abscesses is presented separately. (SeeThe role of imaging tests in the evaluation of anal abscesses and fistulas.)DIFFERENTIAL DIAGNOSISA simple perianal abscess should be distinguished from other conditions that result in an abscess formation and drainage in the presacral, perianal, and perineal regions 8. Some conditions present in the perirectal region (eg, fistula, complex anorectal abscesses), while others can be diagnosed based upon their location (eg, Bartholin cyst, pilonidal cyst).The differential diagnosis of a perianal abscess includes:Anorectal fistulaAn anorectal fistula is the epithelialized track between the abscess and the perirectal skin, and, less common, adjacent organs. The external opening of the fistula can be indurated and drain purulent fluid, but fever is uncommon unless there is an associated undrained abscess. (SeeAnorectal fistula: Clinical manifestations, diagnosis, and management principles.) Presacral epidermoid cystAn infected epidermoid cyst is a discreet nodule that can progressively enlarge, become inflamed, and rupture. (SeeOverview of benign lesions of the skin, section on Epidermoid cyst.)Hidradenitis suppurativaHidradenitis suppurativa can occur in the perirectal area and become infected with purulent drainage. (seePathogenesis, clinical features, and diagnosis of hidradenitis suppurativa (acne inversa)Internal hemorrhoidAn internal hemorrhoid is a normal vascular structure in the anal canal that can become enlarged, engorged, and strangulated, leading to gangrene. A fluctuant mass is palpated on rectal examination (SeeHemorrhoids: Clinical manifestations and diagnosis.)Pilonidal diseasePatients with pilonidal disease can present with an acute abscess. Intergluteal pilonidal abscesses generally occur in the midline, although they may occur off-center. (SeeManagement of intergluteal pilonidal disease.)Bartholin duct abscessAn obstructed Bartholin duct can become obstructed and form an abscess. (seeDisorders of Bartholin gland, section on Bartholin duct abscess)Classification of complex anorectal abscessesA perianal abscess is classified as a simple anorectal abscess. Complex anal abscesses involve different planes in the anorectum, and can have distinct clinical presentations. The complex anal abscesses are classified based upon their anatomic location (figure 3) 6. Complex abscesses are typically associated with complex fistulas and management is also more complicated than that of a simple perianal abscess. (SeeTreatment by site of abscessbelow.)The classification of complex anorectal fistulas includes:Ischiorectal abscess (ischioanal abscess) Ischiorectal abscesses, also referred to as ischioanal abscesses, penetrate through the external anal sphincter into the ischiorectal space and present as a diffuse, tender, indurated, fluctuant area within the buttocks (figure 4).Intersphincteric abscess Intersphincteric abscesses account for only 2 to 5 percent of all anorectal abscesses. They are located in the intersphincteric groove between the internal and external sphincters. As a result, they often do not cause perianal skin changes, but can be palpated as a fluctuant mass protruding into the lumen during digital rectal examination.Supralevator abscess Supralevator abscesses can originate from two different sources: the typical cryptoglandular infection that travels superiorly within the intersphincteric plane to the supralevator space and an inflammatory pelvic process such as perforated diverticular disease or Crohns disease, or a perforated neoplastic process. As a result, it is important to obtain a history of potential sources of pelvic infection.Patients with a supralevator abscess present with severe perianal pain, fever, and sometimes urinary retention. Physical examination usually reveals no obvious external findings. On digital examination, an area of induration or fluctuation can often be felt above the level of the anorectal ring. Because of the paucity of physical examination findings, an abdominopelvic CT scan may be required to establish the diagnosis. (SeeThe role of imaging tests in the evaluation of anal abscesses and fistulas.)Horseshoe abscess A horseshoe abscess is a complex abscess. Horseshoe abscesses form in the potential space posterior to the anal canal that is bounded by the pelvic floor superiorly, the anococcygeal ligament inferiorly, and the coccyx and anal canal. Because of these relatively rigid boundaries, abscesses in this space are forced into the ischiorectal space, where they can be unilateral or bilateral.GENERAL PRINCIPLES OF MANAGEMENTRecommendations for the management of anal abscesses and fistulas have been established by the American Society of Colon and Rectal Surgeons 9. These guidelines are available online at:.The following principles were proposed:Anal abscesses should be drained in a timely manner. Lack of fluctuance should not be a reason to delay treatment.Antibiotics may have a role in special circumstances including valvular heart disease, immunosuppression, extensive cellulitis, or diabetes.A concomitant fistulotomy performed in the same setting as drainage of an anal abscess isnotrecommended because of the high frequency of anorectal dysfunction associated with this procedure. In one trial, for example, 70 patients with an anorectal abscess were randomized to incision, drainage, and fistulotomy with primary partial internal sphincterotomy, or to incision and drainage alone, and patients who underwent fistulotomy were twice as likely to have anal dysfunction (40 versus 21 percent) 10. However, after a median follow-up of 42.5 months, the combined recurrence or persistence rate was significantly higher in patients who did not undergo fistulotomy (40 versus 3 percent). Since primary fistulotomy may be associated with a high rate of anorectal dysfunction, it should be reserved for patients who have refractory symptoms, such as patients with a horseshoe abscess (SeeHorseshoe abscessbelow.).Role of abscess cultureCultures are generallynotrequired in the treatment of an anal abscess, as antibiotic therapy is typically not needed following an incision and drainage in most patients. However, cultures may be useful in the following settings:To distinguish between a cryptoglandular abscess (typically due to colonic flora) and an abscess of the perianal skin (typically due to staphylococcal species)Patients who would typically be treated with antibiotics, including those with valvular heart disease, immunosuppression, extensive cellulitis, and diabetesPatients who have been on multiple courses of antibioticsPatients with pain out of proportion to findings, who may have an unusual pathogen (eg, immunocompromised patients)Patients with leukemia or lymphoma who may have unusual or resistant bacteriaTREATMENT BY SITE OF ABSCESSA perianal abscess can be managed in the office, emergency department, or minor operating room using local anesthesia (figure 3andfigure 5). Complex abscesses should be drained in the operating room, preferably using a regional or general anesthetic, or for smaller lesions, local anesthesia with intravenous sedation.PerianalPerianal abscesses can be readily drained in the outpatient setting. The overlying skin is anesthetized with local anesthesia (eg,lidocainewith bicarbonate) and the cavity is drained with a cruciate incision as close to the anal verge as possible. The proximity of the drainage site to the anal verge is important in minimizing the potential fistula tract. After drainage, the area is cleaned by frequent sitz baths or hand-held showers.ComplexIschiorectalIdeally, an ischiorectal abscess is best drained in the operating room where adequate anesthesia, lighting, and exposure are helpful. However, a limited and well-defined ischiorectal abscess without fistulas can sometimes be drained in the office using local anesthetic.The overlying skin is anesthetized with local anesthesia and the cavity is drained with a cruciate incision as close to the anal verge as possible. The incision for the drainage site should be performed as close to the sphincter complex as possible to minimize the potential for the development of a fistula tract. After drainage, the area can be kept clean by frequent sitz baths or hand-held showers.IntersphinctericIntersphincteric abscesses must be drained in the operating room where a retractor can be placed within the anal canal allowing visualization and access to the abscess cavity through the internal sphincter muscle.SupralevatorSupralevator abscesses can be drained in one of two ways depending upon the site of origin of the abscess. Although the origin is not always readily apparent, abscesses stemming from an extension of an ischiorectal abscess should be drained via the skin overlying the buttock. Abscesses originating from a pelvic process should be drained into the rectum to avoid creating an extrasphincteric fistula.Horseshoe abscessDrainage of a horseshoe abscess is the one setting in which a primary fistulotomy can be performed in the same setting with drainage for anal abscess 11. Fistulotomy should be performed through the posterior midline into the deep post-anal space. A counter incision should be made over the ischiorectal abscess. However, in most patients, the first step is drainage of the horseshoe abscess with one to three incisions. (SeeOperative management of anorectal fistulas, section on FistulotomyandOperative management of anorectal fistulas, section on Fistulotomy and setons.)INFORMATION FOR PATIENTSUpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5thto 6thgrade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10thto 12thgrade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)Basics topics (seePatient information: Anal abscess and fistula (The Basics)SUMMARY AND RECOMMENDATIONSBenign anorectal diseases, including fissures, abscesses, fistulas, and hemorrhoids, are common. However, the prevalence in the general population is probably much higher than seen in clinical practice since the majority of patients with symptoms referable to the anorectum do not seek medical attention.The majority of anorectal abscesses originate from infected anal glands. (SeePathogenesisabove.)Patients with an abscess often present with severe pain in the anal or rectal area that may be constant but not necessarily associated with a bowel movement. Additional symptoms may include fever and malaise. (SeeClinical manifestationsabove.)The physical examination on most patients with a simple perianal abscess reveals an area of fluctuance or a patch of erythematous, indurated skin overlying the perianal or ischiorectal space. In some patients, there are no findings on physical inspection, and the abscess can only be felt via digital rectal examination. (SeeClinical manifestationsabove.)For patients with a suspected anorectal abscess that is not palpable, we perform an MRI of the pelvis. (SeeImaging studiesabove.)An anorectal abscess, fluctuant or not, should be incised and drained. (SeeGeneral principles of managementabove.)For select patients, including those with valvular heart disease, immunosuppression, extensive cellulitis, or diabetes, we use antibiotics in conjunction with incision and drainage of the anorectal abscess. We do not administer antibiotics for other patients. (SeeGeneral principles of managementabove.)For select patients, including those with leukemia, pain out of proportion to clinical findings, and those for whom we administer antibiotics, we obtain a culture and sensitivity on the purulent fluid. (SeeRole of abscess cultureabove.)Patients with a perianal a