Crohn disease can affect the entire gastrointestinal tract, from mouth to anus. It may be confined to the colon alone or involve only the anal canal. Segmental involvement, rectal sparing, fistulas, perianal disease, strictures, and abscess formation are all characteristic of granulomatous colitis. Characteristic "fat creeping" (subserosal extension of fat around the surface of the bowel) and prominent vascularity in the serosa are characteristics of the disease seen on gross inspection. The disease usually affects the bowel in a segmental fashion, leaving so-called skip lesions. Ulcerations and bowel wall thickening occur with areas of sparing in between pathologic areas. Fistulas often form in Crohn disease and may involve small or large bowel, bladder, vagina, uterus, ureter, or skin, most commonly originating from the mesocolic (rather than antimesocolic) border of the bowel. Histologically, the three primary findings in Crohn colitis are transmural inflammation and fibrosis, granulomas, and narrow, deeply penetrating ulcers or fissures.
Although the majority of patients with Crohn disease require surgery during the course of their disease, the indications for surgery are not completely clear-cut. In general, surgery is indicated primarily for complications of the disease, including abscess, fistula, perforation, and obstruction. The decision to operate involves consideration of symptom severity, medical treatment failure or side effects, and operative risks.
Ileocecal Crohn disease may masquerade as appendicitis. Traditionally, patients found to have terminal ileitis at laparotomy for presumed appendicitis, and who have a normal cecum, undergo appendectomy, leaving the diseased ileum in place. However, recent studies demonstrate that the majority of patients found to have Crohn disease at laparotomy for appendicitis required early ileocolic resection; therefore, the traditional advice to leave the diseased bowel in place may be reconsidered.
The ileocecal region is the most common site of Crohn disease. The diagnosis of ileocolic Crohn disease may be delayed up to 1 year. The second surgery rate for ileocolic disease is 44% over 10 years, but this rate may change with the introduction of biologics and other therapies given postoperatively as "maintenance" therapy.
The rectum and anal region can be involved in this chronic inflammatory bowel disease (Figure 4–1), either together (as rectal and perianal Crohn disease) or as separate entities, and the perianal disease often heralds the onset of intestinal symptoms of Crohn disease (see Figure 9–23). Perianal disease on its own has a better prognosis than disease associated with rectal involvement. However, it is important that definitive diagnosis be confirmed by histologic examination, as ulcerative colitis and Crohn disease share similar features. Perianal involvement is present in 3.8–80% of patients, as seen in literature reviews (refer to Armuzzi and colleagues; McClane and Rombeau, listed later), and it recently has been cited as a distinct phenotype of Crohn disease by identification of a susceptibility locus on chromosome 5.
Common locations of chronic anal fissures and other anal conditions.
There is a wide spectrum of presentation of perianal disease, with the perianal skin appearing bluish in active disease. Superficial ulcers may extend into the anal canal or be present on edematous fleshy tags protruding from the anal verge. These ulcers may be painless, whereas deep cavitating ones in the upper anal canal can be painful, causing abscesses and fistulas. The anus can be distorted with fistulating disease and is sometimes described as a "watering can anus." Pain and swelling are common findings, and individuals with fistulas have persistent purulent discharge, pain, and possibly bleeding as well as fever and a preceding history of abscess development. The external opening on the skin is evident, and on digital rectal examination, anoscopy, or proctoscopy, an indurated area in the anal canal corresponding to the internal opening may be obvious. The involved rectal mucosa has a characteristic thickened, nodular feel and a congested and granular appearance.
Perianal lesions are classified as primary or secondary. Primary lesions comprise anal fissure, ulcerated edematous pile, cogitating ulcer, and aggressive ulceration. Secondary lesions consist of skin tags, anal or rectal stricture, perianal abscess or fistula, fistulas of the vagina or bladder, and carcinoma.
An assessment of perianal Crohn disease activity can be made using the Perianal Crohn Disease Activity Index (Table 4–1), which looks at discharge, pain, restriction of sexual activity, type of perianal disease, and degree of induration. Other scoring systems also are available that require additional evaluation. A thorough assessment of intestinal pathology should be undertaken to determine the extent and severity of the disease, because terminal ileal disease sometimes manifests as a perianal fistula, and at other times, medical treatment of intestinal disease improves the outcome or healing of local surgery of perianal disease.
Table 4–1. Perianal Crohn Disease Activity Index. ||Download (.pdf)
Table 4–1. Perianal Crohn Disease Activity Index.
|Categories Affected by Fistulas||Score|
|Minimal mucous discharge||1|
|Moderate mucous or purulent discharge||2|
|Gross fecal soiling||4|
|Pain and Restriction of Activities|
|No activity restriction||0|
|Mild discomfort, no restriction||1|
|Moderate discomfort, some limitation of activities||2|
|Marked discomfort, marked limitation of activities||3|
|Severe pain, severe limitation of activities||4|
|Restriction of Sexual Activity|
|Unable to engage in sexual activity||4|
|Type of Perianal Disease|
|None or skin tags||0|
|Anal fissure or mucosal tear||1|
|<3 perianal fistulas||2|
|≥3 perianal fistulas||3|
|Anal sphincter ulceration or fistulas with substantial undermining skin||4|
|Decree of Induration|
|Gross fluctuance or abscess||4|
Armuzzi A, Ahmad T, Ling KL, et al. Genotype-phenotype analysis of the Crohn's disease susceptibility haplotype on chromosome 5q31. Gut.
Basu A, Wexner SD. Perianal Crohn's disease. Curr Treat Options Gastroenterol.
McClane SJ, Rombeau JL. Anorectal Crohn's disease. Surg Clin North Am.
Pikarsky AJ, Gervaz P, Wexner SD. Perianal Crohn disease: a new scoring system to evaluate and predict outcome of surgical intervention. Arch Surg.
Traditionally, owing to poor or delayed healing, a conservative approach to the management of perianal Crohn disease has been followed. Surgical procedures range from simple suppurative drainage to proctocolectomy and ileostomy, the latter reserved for intractable disease or complications associated with intestinal disease.
Indications for local surgery in perianal Crohn disease are limited to the drainage of pus in abscesses, bothersome fistulas-in-ano that are refractory to medical or nonsurgical management, rectovaginal fistulas, and, in severe proctitis, anal stenosis, or severe recurrent abscesses, proctectomy.
It is important to note that medical therapy alone or surgical therapy alone does not have as high a success rate in the treatment of anal fistulae in Crohn disease as does a combined approach. Surgery, antibiotics, and medical therapy, especially the use of infliximab, used in sequence or combination have shown the best results.
Sciaudone G, Di Stazio C, Limongelli P, et al. Treatment of complex perianal fistulas in Crohn disease: infliximab
, surgery or combined approach. Can J Surg.
Incision & Drainage of Abscesses
A common emergency presentation of perianal Crohn disease is abscess formation requiring incision and drainage to allow maximum drainage of sepsis (Figure 4–2). Appropriate antimicrobial cover is needed when significant cellulitis surrounds the abscess, or the patient is immunocompromised or has cardiac valvular pathology. A cruciate incision or an elliptical excision of skin overlying the area of maximum fluctuance is undertaken under general anesthesia if the abscess cavity is large. Any loculations are then gently broken up with a digit, and the wound is loosely packed (Figure 4–2A). This approach should suffice for superficial abscesses. For deep or high abscesses, placement of a mushroom or Malecot catheter allows adequate drainage and thus prevents premature closure of the surgical incision (Figure 4–2B).
Surgical approach to perianal abscess drainage. A: Simple incision and drainage procedure for an abscess. B: Incision and drainage followed by placement of a mushroom drainage catheter for an abscess. (Reproduced, with permission, from Schwartz DA, Pemberton JH, Sandborn WJ. Diagnosis and treatment of perianal fistulas in Crohn disease. Ann Intern Med. 2001;135:906–918.)
At this time an examination to find any fistulas is undertaken under anesthesia. Usually a probe is inserted through the external opening to delineate the fistulous tract. If any resistance to the passage of the probe is encountered, care is taken to avoid creating false passages. If the internal opening is not evident, injection of dilute methylene blue dye or hydrogen peroxide into the external opening with an angio-catheter may facilitate visualization. The track, if found, is curetted, and a loose seton is inserted to allow drainage. The seton is a thread of foreign material that is passed through a fistula tract and tied into a loop. (Silastic tubing or a vessel loop is preferred because they are soft and can remain in place for prolonged periods.) Drainage of sepsis decreases the risk of further abscess formation and avoids iatrogenic incontinence due to division of any sphincteric muscle, particularly in high anal fistula.
These simple procedures alleviate pain and improve the quality of life in most patients. They also permit magnetic resonance imaging or endoanal ultrasonographic imaging of the anus to delineate more complex fistula tracks or distorted anorectal anatomy. Later, as the sepsis resolves, a more definitive surgical procedure can be undertaken.
Some patients require long-term seton drainage because of the risk of complications that may occur with surgery (eg, delayed wound healing and incontinence). However, healing of the perianal pathology occurs with removal of the seton in some patients.
Surgical Management of Fistulas
Surgical procedures for treating fistula-in-ano in patients with Crohn disease vary, depending on the severity of symptomatology and the complexity of the fistulous track. The following guidelines are suggested: (1) Asymptomatic fistulas need not be treated immediately. However, they often reclose at the level of the skin, and placement of a draining seton is often required to keep the tract open. (2) Simple, low fistulas may be treated by fistulotomy. (3) Complex fistulas may be well palliated with long-term draining setons. (4) Complex fistulas may be treated with advancement flap closure if the rectal mucosa is grossly normal or with placement of a porcine plug, and on rare occasions, a Crohn fistula can be treated with a LIFT (ligation of intersphincteric fistula tract) procedure.
Fistulotomy involves laying open the fistula tract and merging it with the anal canal. This allows the tissues to heal from the inside out. Primary fistulotomy in Crohn disease patients with low, simple fistulas demonstrates excellent healing rates, particularly in the absence of rectal disease. The procedure is contraindicated for complex and high fistulas where division of a large proportion of the anorectal sphincter would be necessary.
When a fistula occurs anterior to the anal canal in a woman, primary fistulotomy almost invariably causes some degree of fecal incontinence. Wound healing occurs in 3–6 months, and complications of fecal incontinence and anal stenosis have been reported. In complex cases, a more conservative surgical approach is taken to minimize the risk of incontinence, by using a noncutting or draining seton. Medical therapy can also be instituted, thus reducing the risk of recurrence. One report found that 85% of patients treated with noncutting setons experienced fistula closure; however, rates of fistula recurrence may be as high as 39% after removal of noncutting setons, highlighting the need for concomitant medical therapy with antibiotics, azathioprine, or 6-mercaptopurine and infliximab. More than one seton may be placed if multiple tracts are present, although fecal seepage and drainage along the seton can be problematic.
In patients with rectal-sparing disease, endoanal or rectal flaps are advocated. These flaps are advantageous because they avoid the risk of incontinence, problems of open wounds, and possibly poor healing that may occur in the presence of sepsis. Apart from flap failure, few complications are seen. Thus, fistulotomy can be performed as a primary procedure or following seton drainage with the use of flaps or interposition grafts.
For longer, more complex fistulae with no evidence of anal sepsis, a porcine plug can be placed in the tract. The tract is usually curetted of all granulation tissue, and the plug is sutured to the anorectal wall with the rectal mucosa covering the plug (see below). A new procedure called a LIFT technique can also be used. The surgeon divides the fistula tract in the intersphincteric groove. All of these techniques for complex fistulae have a lower success rate with Crohn disease. Success is improved when there is no evidence of anorectal sepsis and with quiescent rectal disease.
Bahadursingh AM, Longo WE. Colovaginal fistulas. Etiology and management. J Reprod Med.
Person B, Wexner SD. Management of perianal Crohn's disease. Curr Treat Options Gastroenterol.
Rojanasakul A, Pattanaarun J, Sahakitrungruang C, et al. Total anal sphincter saving technique for fistula-in-ano; the ligation of intersphincteric fistula tract. J Med Assoc Thai.
Rutgeerts P. Review article: treatment of perianal fistulizing Crohn's disease. Aliment Pharmacol Ther.
Schwartz DA, Pemberton JH, Sandborn WJ. Diagnosis and treatment of perianal fistulas in Crohn disease. Ann Intern Med.
Singh B, McMortenson NJ, Jewell DD, et al. Perianal Crohn's disease. Br J Surg.
Endoanal Advancement Flap
An endoanal advancement flap consists of anal mucosa, submucosa, and usually part of the underlying circular muscle. The base of the flap should be twice the width of its apex to ensure adequate blood supply for healing. The optimal depth of the flap is controversial; some surgeons believe that the flap should entail the full thickness of the rectal wall to reduce the chance of flap failure. The fistula tract is cored out or curetted before mobilization, and suturing of the flap distal to the internal opening of the fistula is carried out. Any secondary tracts can be treated by curetting or laying open the tract.
A curvilinear mucosal flap is most commonly used. It involves a semicircular incision starting at the dentate line and continuing proximally for 4–5 cm. The fistula tract is cored out, and the fistula is closed in layers, with mobilization of the flap. The diseased distal portion of the flap is trimmed before the flap is sutured to the mucosal edge of the anus.
If the location of the fistula is high, or there is too much tension on the flap, a linear mucosal flap is used. In this repair, the fistula tract is excised in a linear fashion perpendicular to the dentate line. The defect is closed in layers. The mucosa and submucosa are mobilized on each side and sutured together.
An anocutaneous flap is another option for closing the internal opening. It has the theoretical advantage of not involving any sphincter and can be a more feasible option than an endoanal flap if the internal opening is located distally or if the anal canal is changed by stenosis or scarring after previous surgery or inflammation. The sleeve advancement flap originally described by Berman has also been used to treat anal stricture and a combination of rectal and perianal fistulas.
Using these variations of flaps, healing rates of 68% have been achieved for a curvilinear rectal flap in scenarios of minimal rectal-sparing disease and for rectal ulceration, a sleeve flap and a linear flap for high rectovaginal fistula. Based on a literature review, Sher and colleagues advised using a transvaginal approach to develop a vaginal flap with a protective defunctioning ileostomy for the management of rectovaginal fistula in patients with Crohn colitis. They achieved a success rate of 93% in their series of patients. In cases of high rectovaginal or colovaginal fistula, an approach via the abdomen would be preferable. However, in intractable disease, some women may choose to accept residual fistula drainage over proctectomy or stoma formation.
Bahadursingh AM, Longo WE. Colovaginal fistulas. Etiology and management. J Reprod Med.
Hull TL, Fazio VW. Surgical approaches to low anovaginal fistula in Crohn's disease. Am J Surg.
Sher ME, Bauer JJ, Gelernt I. Surgical repair of rectovaginal fistulas in patients with Crohn's disease: transvaginal approach. Dis Colon Rectum.
Singh VV, Draganov P, Valentine J. Efficacy and safety of endo scopic balloon dilation of symptomatic upper and lower gastrointestinal Crohn's disease strictures. J Clin Gastroenterol.
Diversion of the fecal stream by the creation of an ileostomy or a colostomy has been employed to manage anal fistulas in Crohn disease, an approach first reported by Truelove. A loop defunctioning stoma, which should be easy to reverse, is constructed either laparoscopically or by open surgery. The decrease in fecal flow through the rectum and across the fistula tract allows the rectal mucosa to heal and the fistula to close. Creation of the stoma may improve the results of subsequent anal procedures, and also allows the patient to adjust to the prospect that life with a stoma is feasible. Symptomatic improvement after diversion is not predictable, and new manifestations of perianal Crohn disease can develop. Approximately 50% of patients with symptomatic perianal Crohn disease require permanent fecal diversion.
There are limited indications for fecal diversion in Crohn disease. These include severe perianal sepsis, deep persistent anal ulceration, and complex anorectal or rectovaginal fistula, as well as complications refractory to medical and local surgical measures. In some patients, fecal diversion can be considered before commencement of combination medical therapy. Initially there is a high rate of perianal healing with reversal of the stoma in patient with rectal-sparing disease. However, in individuals with rectal or colonic Crohn involvement, restoration of bowel continuity almost invariably leads to recurrence of perianal symptoms, eventually necessitating proctectomy.
Galandiuk S, Kimberling J, Al-Mishlab TG, et al. Perianal Crohn disease: predictors of need for permanent diversion. Ann Surg.
Yamamoto T, Allan RN, Keighley MR. Effect of fecal diversion alone on perianal Crohn's disease. World J Surg.
Patients with active anorectal disease that fails to respond to medical and previous surgical therapy may require proctectomy with end colostomy. Rates of 10–18% have been reported. Patients who also have colonic involvement require proctocolectomy with permanent end ileostomy. In ill or high-risk patients, this may be performed in two stages, with colectomy and end ileostomy comprising the first procedure, followed by completion proctectomy. In contrast to an abdominoperineal resection for rectal cancer, an intersphincteric dissection may be considered for the perineal component, as this leaves a smaller, more vascularized wound that heals with less morbidity. However, deep fistulating disease or sepsis may make this impossible. When a tension-free closure is not possible, the use of rectus abdominis, gluteal myocutaneous, and gracilis transposition flaps promote healing.
A recognized complication of proctectomy is a persistent perineal sinus. In such cases, it is important to rule out pelvic sepsis or an enteroperineal fistula, which would require resection of the affected bowel. Some patients experience phantom sensations after proctectomy that are analogous to those occurring after limb amputation. Explanation and reassurance is usually sufficient to allay patients' concerns. Persistent perineal pain after proctectomy can be troublesome and may be caused by a neuroma.
Patients with long-standing Crohn disease, like those with ulcerative colitis, are at increased risk (3.7%) of developing adenocarcinoma as well as squamous cell carcinomas. This increased risk has been attributed to an early onset and prolonged duration of disease. The incidence of carcinoma is 0.7% in patients with perineal Crohn disease. Patients with adenocarcinoma require proctectomy. Those with squamous cell carcinoma may be considered for chemoradiotherapy; however, the functional outcome may be unsatisfactory. Therefore, proctectomy may be the preferred option. The diagnosis is usually made based on examination of biopsy specimens and brushings of the curetted fistulous tract.
Rius J, Nessim A, Noguerasa JJ, et al. Gracilis transposition in complicated perianal fistula and unhealed perineal wounds in Crohn's disease. Eur J Surg.
Recent innovative therapy involves the use of adhesive products. Several studies have reported on fibrin glue treatment of anal fistula using both autologous fibrin tissue adhesives and commercially available fibrin glue. The adhesive is instilled in the fistula tract after curetting, and sometimes irrigation of the tract, to allow glue adhesion to the tissue. Insertion of the fibrin glue is continued until glue appears at the internal opening of the fistula. The sealant not only acts as a closing plug for the fistula, but also as the substrate for the in-growth of fibroblasts. The technique is not suitable for fistulas with extensions.
The reported success rates in patients have varied from 40% to 85%, with a mean of 67% for the various materials. Buchanan and colleagues reported long-term healing of only 14%, whereas Sentovich showed a healing rate of 60% when all patients had a draining seton preoperatively and the internal opening was closed with a suture at the time of glue instillation. In a later review by Swinscoe and colleagues of 12 studies, the overall healing rate was 53%. However, in patients with Crohn disease, fistula results have been considerably lower. Recent data have shown no value in using fibrin glue over fistula surgery without glue. Currently, we do not recommend or use fibrin glue for the treatment of fistulae. The use of human granulocyte colony-stimulating factor instead of fibrin glue has been shown to heal perianal Crohn-associated fistula in some patients.
Johnson and colleagues introduced a new method of closure for anal fistula with a bioprosthetic plug. The conically shaped plug, made of porcine collagen, is pulled into the primary tract through the internal opening until it fills out the whole length of the tract. Both ends of the plug are secured with sutures, and at the internal opening, the end of the plug is covered with mucosa and also preferably with internal sphincter. The remaining external opening is left open for drainage. Champagne and colleagues reported a success rate of 83% with a median follow-up of 12 months for high cryptoglandular anal fistulas, and the method has also been used in a smaller group of patients with Crohn fistulas reported by O'Connor and colleagues. However the exact place that these modalities have in the management of Crohn fistula remains unclear, but their use does not preclude other surgical procedures should the treatment fail.
Asymptomatic fissures, hemorrhoids, and skin tags in Crohn patients should be left alone, and if surgery is requested, the patient should be informed of complications such as poor healing, stenosis, incontinence, and ulcer formation. Anal ulcers are likely to be worsened by surgery, and a trial with medical therapy should be instituted to promote healing. In refractory symptomatic anal fissures without proctitis, lateral sphincterotomy is indicated. Symptomatic strictures should be cautiously dilated with Hegar dilators or an endoscopic balloon, as perforation is a risk. The stricture may be primary or occur as a complication of anorectal or ileal pouch surgery performed on the basis of an incorrect preoperative diagnosis of ulcerative colitis or indeterminate colitis. Severe strictures that do not respond to dilation may require an advancement flap (in low anal strictures) or ultimately fecal diversion or proctectomy (in anorectal stenosis).
Given the unpredictable disease process of perianal Crohn fistulas and the variety of surgical options, management should be individually tailored, using combined medical and surgical approaches to offer the patient an improved quality of life.
Buchanan GN, Bartram CI, Phillips RK, et al. Efficacy of fibrin sealant in the management of complex anal fistula: a prospective trial. Dis Colon Rectum.
Champagne BJ, O'Connor LM, Ferguson M, et al. Efficacy of anal fistula plug in closure of cryptoglandular fistulas: long term follow-up. Dis Colon Rectum.
Cintron JR, Park JJ, Orsay CP, et al. Repair of fistulas-in-ano using fibrin adhesive: long-term follow-up. Dis Colon Rectum.
Johnson EK, Gaw JU, Armstrong DN. Efficacy of anal fistula plug vs. fibrin glue in closure of anorectal fistulas. Dis Colon Rectum.
Lindsey I, Smilgin-Humphreys MM, Cunningham C, et al. A randomized, controlled trial of fibrin glue vs. conventional treatment for anal fistula. Dis Colon Rectum.
Loungnarath R, Dietz DW, Mutch MG, et al. Fibrin glue treatment of complex anal fistulas has low success rate. Dis Colon Rectum.
O'Connor L, Champagne BJ, Ferguson MA, et al. Efficacy of anal fistula plug in closure of Crohn's anorectal fistulas. Dis Colon Rectum.
Sentovich SM. Fibrin glue for anal fistulas: long-term results. Dis Colon Rectum.
Swinscoe MT, Ventakasubramaniam AK, Jayne DG. Fibrin glue for fistula-in-ano: the evidence reviewed. Tech Coloproctol.