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Spring 2005 |
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ANAL ABSCESS / FISTULA Anal abscesses and fistulas continue to be common problems treated by general and colon and rectal surgeons. These very troubling problems start with infection in the anal crypts, glands at the transition from anal skin to rectal mucosa. There are 6-8 of these glands but the glands in the anterior and posterior midline are the ones that most commonly get infected. Some of these glands penetrate through the entire thickness of the internal anal sphincter muscle. Once infected the purulent process with dissect to the perianal skin. A rapidly developing painful mass at the anus should suggest either an acutely thrombosed external hemorrhoid or a perianal abscess. Inspection is usually sufficient to differentiate the firm but not inflamed thrombus right at the anal verge from the inflammatory mass more laterally located. The position of the inflammatory mass depends on the course of the tract. Some dissect distally through the intersphincteric plane to the anal verge. Others will penetrate in a more lateral fashion, penetrating radially through the external anal sphincteric to the ischiorectal fat. Rarely, the tract will start proximally then exit above the sphincter muscles out to the ischiorectal fat. Antibiotics are rarely adequate treatment of perirectal abscess but may be needed if there is cellulitis extending beyond the abscess. Surgical drainage is usually needed. Superficial infections can be drained in the office or the ER under local anesthesia but some require general anesthesia due to the size or extent of the infection or abscess. In some patients the abscess will not be obvious due to location deep to the subcutaneous portion of the external sphincter muscles, in the anterior or posterior deep anal space (see figures at right). These patients have acute pain and tenderness but no obvious mass to inspection. They may not have an obvious mass on rectal examination either, but always have focal tenderness. Examination under anesthesia may be required to confirm the diagnosis. Radial incision into the deep space with careful preservation of the subcutaneous portion of the sphincter will allow adequate drainage without compromise of stool control. Small mushroom catheters are often helpful for this and allow the space to collapse. About 50% of abscesses will heal completely after drainage of the acute abscess. The remainder will convert to a chronic anal fistula. The treatment of the resultant fistula depends on the course of the tract in relation to the sphincter muscle. Superficial tracts can be opened |
safely and will heal readily. Deeper tracts would cause incontinence if opened and need more conservative treatment. Long term drainage (6+ weeks) with a vessel loop, occlusion with fibrin glue and advancement flap are alternatives that preserve sphincter muscle.
REMEMBER: COLORECTAL CANCER IS PREVENTABLE!!! |
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Kitsap ColoRectal Surgery, Johnny B. Green, MD, FACS, FASCRS | ||
