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SSAT Patient Care Guidelines

Treatment of Perineal Suppurative Processes


The diagnosis and management of suppurative processes in the perineum and surrounding areas can be a challenge for physicians. Abscess, fistula, pilonidal cyst and abscess, hidradenitis suppurativa and sexually transmitted disease are the most common of these maladies and will be addressed in these guidelines.

Clinical Presentation

Most anorectal infections originate in the cryptoglandular area located in the anal canal at the level of the dentate line. Cryptoglandular obstruction may result in four types of abscesses: perianal, ischiorectal, intersphincteric, and supralevator. These are categorized by their anatomic relationship to the external sphincter complex. A small number of anorectal abscesses have a non-cryptoglandular etiology such as seen in Crohn's disease, atypical infection (e.g., tuberculosis, lymphogranuloma venereum), malignancy, or trauma. Recently, community acquired MRSA has been cultured more frequently from perianal abscesses. MRSA abscesses do not seem to be associated with cryptoglandular disease and may result primarily from a skin infection such as hidradenitis. Particularly virulent organisms, immunologic deficiency in the patient (e.g., poorly controlled diabetes, HIV, obesity), or localized scarring from previous operations can make the diagnosis more challenging. Fever, rigors, and shock may occur before more subtle localized findings. Pain and swelling are the most frequent complaints. Bleeding, purulent discharge and fevers may also be present. Delayed diagnosis and treatment may result in progression to local gangrene in these atypical patients. The long term outcome of patients who progress to Fournier’s Gangrene (mixed flora infection with edge of tissue necrosis) is poor.

A perianal abscess is usually evident at the anal verge, and patients present with the rapid onset of acute pain at the anal margin. An inflammatory process in the soft tissues of the inner aspect of the buttock would more commonly indicate a perirectal/ischiorectal abscess. These abscesses present more slowly (at times over several days). Skin changes may be slow to appear as well. Pelvic pain and dysuria may herald a supralevator abscess. Constant pelvic or rectal pain, which is exacerbated by defecation but associated with no external findings, is more typical of an intersphincteric process which extends cephalad from the dentate line, in the space between the circular muscle fibers of the internal sphincter and the longitudinal muscle fibers of the rectal wall.

Progression of cryptoglandular disease to a chronic phase results in fistula-in-ano. The majority of patients with a fistula-in-ano have a history of abscess development with persistent drainage, pain and possibly bleeding. The external opening on the skin is evident, and digital rectal exam, anoscopy or proctoscopy may reveal an indurated area in the anal canal corresponding to the internal opening. If there is any suspicion of an underlying disease such as Crohn’s or immune suppression, additional diagnostic studies should be undertaken prior to the formal treatment of the fistula. Adjunctive imaging should also be considered in more complex perirectal infections (see below). Categorization of the fistula depends on the extent of anal sphincter encircled by the tract. This in turn affects the choice of treatment. Clear delineation of the tract is therefore very important.

Pilonidal cysts initially present as an abscess and/or cellulitis in the sacrococcygeal area. They are twice as common in men as women and present at mean ages of 21 and 19 years, respectively. Affected individuals tend to be more hirsute. Spontaneous drainage often occurs through the dome of the abscess cavity away from the midline, followed by chronic drainage from the secondary sinuses. Some of these sinuses may track toward the anus, potentially being confused with a fistula-in-ano or hidradenitis suppurativa. Hidradenitis results from infection of occluded apocrine sweat glands. Consequently, it can occur in the perineal/perianal region, in the areolar area of the breasts and quite frequently in the axillae. It is most commonly seen in the second thru fourth decades of life and is thought to be hormonally influenced, with women affected three times as frequently as men.

Diagnostic Studies

While history and physical examination are sufficient to diagnose the majority of simple abscesses or fistulae, patients with more complex problems may benefit from adjunctive imaging, such as transrectal ultrasound, CT or MRI scans. Indications for adjunctive imaging include: a history of Crohn’s disease, rectal cancer, pelvic radiation, complicated fistulae not responding to primary therapy, recurrent perirectal infections, diabetes, immunosuppression, and neutropenia. CT or MRI should also be considered when a supralevator or abdominopelvic abscess is considered based upon signs and symptoms of lower abdominal or pelvic pain, rectal fullness, or the presence of purulence in the rectum. Imaging may also be useful in the presence of a horseshoe abscess, where an infected posterior midline gland may decompress into the communicating spaces around the anal canal and rectum (superficial postanal, deep postanal, supralevator, and ischiorectal on both sides). This information can help the surgeon drain the appropriate space(s) in the operating room. The horseshoe abscess is the most common source of Fournier’s gangrene related to anal suppurative disease because it is the most difficult to detect and treat completely.


In the absence of an obvious anal fissure or thrombosed external hemorrhoid, anorectal pain that prevents a digital examination necessitates an examination under anesthesia and/or appropriate imaging. Needle aspiration can demonstrate a collection of pus that is accessible to percutaneous drainage. As with any abscess, incision and drainage is the definitive form of therapy. Admission to the hospital for intravenous antibiotics should also be considered when there is significant cellulitis surrounding the abscess or when the patient is immunocompromised or has cardiac valvular pathology.

Perianal and ischiorectal abscesses can usually be drained using local anesthesia if they have tracked to the subcutaneous area. The preferred surgical approach includes a simple radial incision or cruciate incision of adequate size to unroof the cavity and allow complete drainage of the purulent material, as close to the anal verge as possible. This technique avoids unnecessary deformities and will result in the shortest possible fistulous tract, for those patients who proceed to the chronic phase of cryptoglandular disease. If the abscess cavity is large and the procedure is being performed under general anesthesia, digital exploration should be performed to break up any loculations. Packing of the wound is only necessary for initial hemostasis and a mushroom catheter can keep the cavity drained until the infection resolves. Adequate drainage, followed by frequent sitz/tub baths, especially after bowel movements, will reduce the risk of continued infection and recurrence. If an internal opening is found at initial treatment, it should be probed to clarify the tract (fistula). A loosely tied seton of silk or silicone vessel loop serves as a drain until definitive therapy can be undertaken. A primary fistulotomy should only be performed in the most superficial of fistulas (no sphincter muscle involved) by an experienced surgeon.

Surgical management of a chronic anal fistula depends upon adequately establishing the course of the fistula tract. Pressure to overcome any resistance to the passage of a probe should be avoided so as to prevent the creation of false passages. If the internal opening is not evident, injection of dilute dye or hydrogen peroxide into the external opening with an angiocatheter may facilitate the visualization. Judicious unroofing of the observable external tract may also allow better recognition of the entire tract. Pre operative trans-anal ultrasound and fistulography are useful diagnostic modalities to be considered. MRI may also delineate the path of the tract. Operative goals for superficial perianal intersphincteric or very superficial transphincteric anal fistulae are to open the tract and remove the epithelial lining by curettage, electrocautery, etc. More complex tracts involving a significant amount of sphincter muscle require different surgical techniques to avoid division of sphincter muscle and resulting incontinence. These more complex fistulae may be treated with non-cutting setons, fibrin glue, ablation, rectal advancement flaps, anal fistula plugs, or combinations of these.

Treatment in the acute phase of a pilonidal cyst/abscess involves simple incision and drainage to unroof the lateral extension of the abscess. Antibiotics are used if there is significant cellulitis. Any septations should also be disrupted. Because hair and particulate matter are often found within the cavity/sinuses, the use of depilatory cream should be considered to lower the risk of recurrence. The development of chronic sinuses will require further operative intervention for removal. A number of surgical techniques have been described for management of the chronic phase including primary closure vs healing by secondary intention. Off-midline incisions appear to be associated with lower morbidity and better healing than midline incisions. All gluteal cleft pits should be removed during the definitive procedure.

Hidradenitis suppurativa results from occluded apocrine or follicular ducts infected with skin bacteria. These glands tend to rupture into adjacent glands or cavities to coalesce into larger subcutaneous abscesses. Unless there are abscesses that need operative drainage, local symptomatic therapy and antibiotics for the cellulitis are initially adequate. Given the chronic inflammatory nature of the condition, medical regimens that involve other antiflammatory strategies have also been employed. Patients may respond to simple incision and drainage, and wound healing by secondary intention is frequently chosen. Complete excision of the skin affected by the process is usually necessary to achieve resolution. Vacuum dressing therapy or tissue transfer may be necessary for healing in these extreme cases. In order to optimize the healing of complicated wound closures, especially near the anus, a temporary diverting colostomy should be considered.


The potential effect on continence is an important consideration in the treatment of any anorectal suppurative condition. Incision and drainage should be completed with as little damage to the sphincter complex as possible. The risks of fecal incontinence and possible recurrence of the suppurative process should be discussed with the patient before any operative intervention on the anorectum.

Patients with anorectal infections who don’t respond to simple incision and drainage or who meet other criteria described above should undergo adjunctive imaging. Horseshoe abscesses may require additional procedures and may be best managed in the chronic phase by referral to a specialist. Because of the significant risk for chronic morbidity following an anal fistulotomy in patients with Crohn’s disease, appropriate evaluation of the rectum and entire GI tract should be performed. While simple Crohn’s fistulae without proctitis may be treated with a fistulotomy, more complex fistulae, or those associated with active proctitis, should be treated with a multidisciplinary approach including drainage setons and specialized medical therapy. Closure of the internal opening of the fistula should only be considered when the rectal mucosa shows no active disease.

When treating chronic hidradenitis, as with any non-healing lesion, a malignant process should be ruled out by biopsy. Topical steroids should be avoided because they compromise normal skin resistance to trauma and infection. While topical anesthetic agents provide temporary comfort, they are often sensitizing and can worsen irritation and inflammation. Persistent, unilateral lesions should always be biopsied to rule-out a malignant process.

Qualifications for Performing Surgery on Perineal Suppurative Processes

The qualifications of a surgeon to perform any operative procedure should be based on education, training, experience and outcomes. At a minimum, the surgical treatment of perineal suppurative processes should be carried out by surgeons who are certified or eligible for certification by the American Board of Surgery, the American Board of Colorectal Surgery, the Royal College of Physicians and Surgeons of Canada, or their equivalent.

Suggested Readings

Corman M. Anorectal abscess and Anal fistula. 1998. In Colon and Rectal Surgery, 4th edition. Lippincott-Raven, pub. Pp 224-271.

Gordon PH. Anorectal abscesses and fistula-in-ano. 1999. In Principles and Practice of Surgery for theColon, Rectum and Anus, 2nd edition. Gordon PH, Nivatvongs S, ed. Quality Medical Publishing, pub. Pp 241-286.

Friend WG. Pruritus Ani. In Fazio V (ed): Current Therapy in Colon and Rectal Surgery. Toronto, BC Decker Inc., 1990:42-45.

Hyder SA, Travis SP, Jewell DP, McC Mortensen NJ, George BD. Fistulating anal Crohn's disease: results of combined surgical and infliximab treatment. Dis Colon Rectum. 2006 Dec;49(12):1837-41.

Karulf R and Perry WB. Pilonidal Disease. 1998. In Fundamentals of Anorectal Surgery, 2nd edition. Beck D and Wexner S, eds. Saunders, pub. Pp. 225-232.

McCallum IJ, King PM, Bruce J. Healing by primary closure versus open healing after surgery for pilonidal sinus: systematic review and meta-analysis. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD006213. Review.

Mekkes JR, Bos JD. Long-term efficacy of a single course of infliximab in hidradenitis suppurativa. Br J Dermatol. 2008 Feb;158(2):370-4. Epub 2007 Nov 28.

Ortega AE, Lugo-Colon H, Diaz-Carranza A, Kaufman HS: Computed Tomography and Magnetic Resonance Imaging in Abscess and Anal Fistula. In: Pescatori M, Regadas FSP, Regadas SMM, Zbar AP (eds). Imaging Atlas of Pelvic Floor and Anorectal Diseases. 1st ed., 61-71, 2008.

Waters GS, Nelson H. Perianal Hidradenitis Suppurativa. 1998. In Fundamentals of Anorectal Surgery, 2nd edition.

Beck D and Wexner S, eds. Saunders, pub. Pp. 233-236.

Key Words - Perianal abscess, perirectal abscess, fistula-in-ano, Crohn’s disease, anorectal abscess, hidradenitis suppurativa, pilonidal abscess, pruritis ani

Board Approved February 21, 2004
Revised & Board Approved 05/30/2009

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SSAT Patient Care Committee Guidelines

These patient care guidelines were written for the primary care physicians on a variety of digestive diseases to assist on when to refer the patient for surgical consultation.
Their goal is to guide PRIMARY CARE physicians to the appropriate utilization of surgical procedures on the alimentary tract or related organs and they are based on critical review of the literature and expert opinion. Both of the latter sources of information result in a consensus that is recorded in the form of these Guidelines. The consensus addressses the range of acceptable clinical practice and should not be construed as a standard of care. These Guidelines require periodic revision to ensure that clinicians utilize procedures appropriately but the reader must realize that clinical judgment may justify a course of action outside of the recommendations contained herein.

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