Anorectal Abscess and Fistula-in-Ano: Evidence-Based Management
Section snippets
Pathophysiology
Anorectal abscess occurs commonly in normal, healthy individuals. The most widely recognized cause is described in the cryptoglandular theory, which suggests that an anal crypt gland becomes obstructed with inspissated debris and leads to infection. These glands penetrate the anal sphincter complex to varying degrees, and the suppuration tends to follow the path of least resistance. The abscess collects in whichever anatomic space the gland terminates, or wherever the path of least resistance
Classification
Anorectal abscesses are classified based on their location. Four types of anorectal abscesses are commonly described: perianal (superficial), ischiorectal (perirectal), intersphincteric, and supralevator. Perianal is the most common type and is the simplest to treat. The collections are located in the superficial perianal tissues and are typically located close to the anal verge. Ischiorectal abscesses are located more deeply in the ischiorectal fossa and may communicate to the contralateral
Treatment
The treatment of anal fistula is dictated by the classification and the amount of sphincter complex that is involved with the tract. Simple fistulas, intersphincteric, and low trans-sphincteric of cryptoglandular origin, can be treated easily with a fistulotomy with minimal risk to continence. Complex fistulas, high fistulas, and those related to inflammatory bowel disease must be treated through more intricate methods. The primary surgical approach to successful resolution of an anal fistula
Medical management
The major morbidity associated with the surgical treatment of fistula-in-ano is fecal incontinence. Kim and colleagues9 retrospectively studied 404 male patients with fecal incontinence and found that in patients younger than 70 years, the second most common association was a prior surgical fistulotomy or hemorrhoidectomy. Lindsey and colleagues10 performed anal manometry and endoanal ultrasonography in 93 patients being evaluated for fecal incontinence after anal surgery. They had universal
Preoperative planning
Simple submucosal, intersphincteric, and low trans-sphincteric fistulas are effectively managed by fistulotomy with minimal risk to fecal continence. In the past, the patient had to undergo an examination under anesthesia to determine the type of fistula and the amount of sphincter mechanism that was involved. If a simple fistula was found, then definitive management was typically undertaken. Complex fistulas would be managed through staged approaches. These decisions hinge on the clinician's
Fibrin glue
Because traditional methods to repair complex fistulas, including fistulectomies, fistulotomies, and advancement flaps, have resulted in high rates of incontinence, investigations into less invasive procedures have been performed. Fibrin glue first made its appearance in surgery during World War I, when it was used for hemostasis, and then later in the 1940s as a sealant for skin-graft procedures.24 In 1992, Hjortrup and colleagues25 first used it as a sealant for anal fistulas and since that
Fistula plug
Fibrin glue studies failed to achieve results that were reproducible, but did show promise in muscle-sparing, noninvasive operative techniques for anal fistulas. This result led to the development of additional sphincter-sparing therapies. The concept of a plug was first introduced in 2006 by Robb and colleagues40 and Johnson and colleagues41 with the idea that securing the plug into the primary opening of a fistula tract could close the tract more reliably than previous procedures, without
Advancement flap
Before the advent of the collagen anal fistula plug or the use of fibrin glue, surgeons devised the endorectal/endoanal advancement flap as a sphincter-sparing method to treat complex anal fistulas. It was believed that this would preserve continence because there is no surgical division of the anal sphincter complex. There are several methods, but the technical aspects common to all methods are cleaning/debridement of the fistula tract, mobilization of a well-vascularized rectal mucosal or
Setons
Setons are a viable treatment option for high trans-sphincteric fistulas, fistulas involving greater than half the bulk of the sphincter complex, and anterior trans-sphincteric fistulas in women. Setons are preferred to surgical fistulotomy because of the high incontinence rate associated with that technique in these patient populations.67, 68 The risk of and concern about incontinence are not eliminated with the use of cutting/tight setons. More conservative sphincter-sparing measures that do
Fistulotomy
Fistulotomy is still considered the standard by many surgeons for low, simple anal fistulas, such as submucosal, intersphincteric, and low trans-sphincteric fistulas (Fig. 7).67, 79 According to ‘The practice parameters for the treatment of perianal abscess and fistula-in-ano,’ completed by Whiteford and colleagues79 in 2005, fistulotomies may be used to treat simple anal fistulas in cryptoglandular disease and simple, low Crohn's fistulas that are symptomatic. Their definition of simple
Newer methods of treatment
The search for the optimal treatment of anal fistula continues because of disappointing success rates with sphincter-sparing options and high incontinence rates associated with sphincter dividing procedures. The ligation of the intersphincteric fistula tract (LIFT) procedure was first described in Thailand by Rojanasakul.88 This is a procedure in which a small incision is made in the intersphincteric groove (much like an open internal sphincterotomy) just over where the fistula tract crosses
Summary
The surgical management of fistula-in-ano is driven by the amount of sphincter complex that is involved with the tract, and the potential coexistence of Crohn's disease. The preferred method of management is dictated by these factors. Sphincter-sparing methods have lower success rates than nonsphincter-sparing techniques, but come with little to no risk of fecal continence. The first line of treatment of this disease should focus on methods that do not require any sphincter division. These
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