Surgical Approaches to Perianal Disease

Garth S. Herbert

Scott R. Steele

INTRODUCTION

The phenotypic manifestations of Crohn’s disease (CD) and ulcerative colitis (UC) can be very different. While CD is associated with perianal pathology in up to 80% of patients, perianal disease is rare in UC (1). The presence of perianal findings in a patient carrying the diagnosis of UC should trigger providers to confirm that CD has been adequately excluded. Within the Crohn’s population, the incidence of perianal disease varies along with the presence of CD in other intestinal locations. Those patients with perianal disease are far more likely to have concomitant distal intestinal involvement than proximal disease. In one review of 66 patients with symptomatic perianal disease, 82% had associated colonic involvement (2). The importance of a thorough anal examination cannot be overemphasized, even for those patients without a prior diagnosis of CD. Perianal complaints may be the presenting sign or symptom in up to 30% of Crohn’s patients, even predating the development of proximal intestinal manifestations (2,3).

Perianal CD is typically associated with large, bluish hemorrhoidal skin tags or “elephant ears,” multiple fistulas (including the extreme form of “watering can perineum”), and fissures off the midline, but it can also present in ways similar to non-IBD perianal pathology. The relative incidence of perianal manifestations for CD is listed in Table 11.1. Although some conditions are treated in the same manner whether or not a patient has associated IBD, others are managed differently when inflammatory bowel disease (IBD) is present. In addition, as both disease recurrence and diarrhea are characteristic of CD, special consideration for future function and sphincter preservation are of special concern. In the following sections, we will discuss the diagnosis, medical treatment, and subsequent surgical management of various perianal conditions associated with IBD.

DIAGNOSIS

Accurate diagnosis begins with a thorough history and physical examination. While rectal bleeding is a significant component of UC, it is much less common in patients with CD (4). The history can provide insight, with particular emphasis being placed on the presence or absence of drainage suggestive of fistulas, pain indicating possible fissures or abscesses, and systemic symptoms. Abdominal pain, weight loss, and/or increasing diarrhea may indicate more proximal intestinal disease activity. Examination of the perianal area may reveal findings characteristic of CD, such as prominent, edematous skin tags, multiple fistulous openings, or anal fissures (particularly those off the midline or multiple fissures). Findings in patients with UC are generally bland or may include more common anorectal pathology seen in patients without underlying IBD.

Digital rectal exam and anoscopy are essential steps that can identify areas of active inflammation, strictures, or internal fistula openings. Attention must be directed toward assessment of the anorectal mucosa to determine if active proctitis is present, as it may play a role in disease management. When examination findings suggest CD, a staging evaluation combining endoscopy and select radiologic
studies is advised. Biopsies should be performed on all suspicious perianal lesions. In patients with an established diagnosis of CD, annual anorectal surveillance has been suggested for those patients with chronic severe anorectal disease, rectal remnant after diversion, anorectal stricture, or any bypassed segment in a patient with sclerosing cholangitis (5).

TABLE 11.1 Relative Incidence of Perirectal Manifestations of Crohn’s Disease (2,6,31,38)

Process	Incidence (%)
Perianal abscess	36-86
Fistula-in-ano	33-87
Anal fissure	32-44
Anorectal stenosis	7-37
Skin tags	15

MEDICAL TREATMENT

Medical treatment to control diarrhea from CD is helpful in addressing perianal disease. Antibiotics have been shown to be effective, especially in fistulizing disease, almost exclusively in open-label trials. Metronidazole improved perianal symptoms (at least temporarily) in over 90% of patients in one series (6). A fluoroquinolone is also a reasonable choice. Each antibiotic can bring toxicity; the peripheral neuropathy seen with extended exposure to metronidazole is particularly important, as it is sometimes permanent.

There are limited data for azathioprine and 6-mercaptopurine (6-MP) for fistulizing CD (7). Cyclosporine and tacrolimus are supported by limited studies (8,9). Infliximab, a monoclonal antibody against tumor necrosis factor (TNF), has been shown to increase the healing rate of perianal fistulas. Present and colleagues found three doses of infliximab over a 6-week period achieved complete closure of perianal fistulas in 46% of patients in one study (10). Other anti-TNF agents, such as adalimumab and certolizumab pegol, hold promise.

Regardless of the medical therapy used, the decision to embark on surgical treatment for perianal CD must be weighed against the extent of each patient’s symptoms. Due to the propensity of perianal disease to recur over the course of the patient’s life, the surgical approach must be deliberate and the patient must be educated as to realistic goals.

SURGICAL TREATMENT OF PERIANAL CD

Skin Tags and Hemorrhoids

Patients with CD may have any condition seen in patients without IBD. The management of such problems must be tempered by the underlying illness. Surgical treatment of hemorrhoids in CD was initially discouraged due to the high complication rate, which includes poor wound healing and the development of severe perineal sepsis that sometimes required proctectomy (11). However, recent reports suggest that select patients may be treated surgically with a low rate of complications (12). Proper patient selection, in part, depends on identifying those with optimal medical control of their disease and those without significant ongoing proctitis.

Skin tags may occur in up to 15% of patients with perianal CD (6), and are most commonly asymptomatic, although they may cause difficulty with hygiene due to
their potentially large size. As with surgical management of hemorrhoids in CD, skin tag excision may result in perineal sepsis or chronic, nonhealing wounds. As many as 30% of skin tags associated with CD may resolve spontaneously, further underscoring the role of conservative management (13,14).

Perirectal Abscess

Patients with CD may develop any one of the classical perianal, ischiorectal, intersphincteric, supralevator, or horseshoe abscesses. Approximately 50% to 80% of patients with perianal CD experience a perirectal abscess over their lifetime (1,2). Unfortunately, of those who develop an initial abscess, >50% will develop a recurrent abscess within 2 years (1).

There is some disagreement with regard to the etiology of perirectal abscesses in CD—whether they are cryptoglandular in origin, or whether they develop secondary to a cavitating ulcer eroding through the anal canal (15). Regardless of the underlying etiology, uncomplicated perirectal abscesses can be treated with simple incision and drainage. Due to the potential for fistula formation, it is important to keep the incision as close as possible to the anal verge. Often, gauze packing or a conduit drain such as a Penrose is placed into the cavity to promote drainage. These dressings may need to be changed during the course of healing. It is well accepted, however, to place packing at the initial drainage procedure, remove it the following day, and allow the wound to heal by secondary intention. Another well-described technique used in larger cavities consists of placing a mushroom-tipped catheter into the abscess to permit drainage and to facilitate closure of the cavity around the catheter (2,13). Given that abscesses commonly occur in conjunction with fistulas, an added benefit of this technique is to permit identification of an internal opening by injection of dye once the inflammation has resolved (13).

Perirectal abscesses are one manifestation of CD that leave little question regarding the need for surgical treatment. A thorough search for and drainage of all sepsis is required as transmural CD may result in more extensive involvement than is initially apparent. Of note, an underlying fistula is frequently discovered at the time of abscess drainage; this can alter and even complicate management.

Anal Fistula

Anal fistulas are a common diagnosis in patients with perianal CD and frequently present simultaneously with perianal abscesses. For low-lying simple fistulas involving minimal external anal sphincter (and in the absence of active proctitis), fistulotomy is safe and effective (2,6). These fistulas are often multiple, complex, and may have extensive sphincter involvement. Given the chronicity of the disease and high frequency of relapse, maximum preservation of sphincter function is essential. Thus, prior to embarking on any fistulotomy, surgeons should consider all relevant patient factors, particularly the extent of disease, sphincter status, rectal compliance, presence of active proctitis, and any prior anorectal operations.

For complex fistulas associated with CD, fistulotomy is generally avoided due to the high risk of incontinence. Rather, long-term (>6 weeks) placement of loose setons, such as vessel loops or silastic catheters, has been advocated by many authors to control drainage and allow inflammation to resolve (1,2

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