The surgical treatment of perianal fistulas in Crohn’s disease is based on the fistula type (low or high) and, more importantly, the presence of active proctitis. For those with low fistula in ano, fistulotomy still has a role. The data to date support the conclusion that, for low fistulas with no active disease, surgery for Crohn’s disease patients is as effective as in non-inflammatory bowel disease patients. Interestingly, a University of Minnesota series of 41 fistulas in 33 patients without active proctocolitis showed a 93% healing rate at 6 months with standard fistulotomy.
As expected, Nordgren and colleagues (1992) found a healing rate of only 27% in those treated with fistulotomy who had active proctocolitis and 83% in those without active disease. More recently, Scott and Northover (1996) documented in patients with Crohn’s disease that in simple fistula, low fistulas without active disease, fistulotomy is acceptable treatment. For those with active disease, the fistula should be treated with a noncutting Seton and concomitant medical therapy.
High or Complex Fistula
Those fistulas which involve a significant portion of the anal sphincter, such as high transsphincteric, supra-sphincteric, or extrasphincteric, including rectovaginal and anal vaginal fistula, as well as those with primary openings in the rectum, require a more thoughtful approach. The type of surgical treatment is again dependent on the type of fistula and the presence and severity of rectal disease. Patients with complex fistulas often required proctectomy because of the failure of both medical and surgical therapy. More recently, techniques such as Seton placement, fibrin glue, advancement flaps, and, of course, anti-tumour necrosis factor-a infusion therapies, have all been used successfully.
The use of a noncutting Seton is the most common and effective treatment modality in use for Crohn’s disease patients with complex fistula in ano. A Seton is a nonabsorbable suture (or vessel loop) that is placed through the fistula tract. Passing it through the cutaneous opening of the fistula and out of the associated anal canal opening allows the two ends to be tied loosely together. Although sometimes these draining setons are uncomfortable for the patient, the risk of recurrent abscess is minimized while aggressive medical therapy is being instituted. In a case series of 27 patients with fistulizing Crohn’s disease, Scott and Northover reported that 85% of patients treated with noncutting Setons experienced fistula closure.
Others have looked at long-term Seton placement and have reported excellent initial results. However, rates of fistula recurrence maybe as high as 39% after Seton removal, highlighting the need for concomitant medical therapy with antibiotics, azathioprine, or 6-mercaptopurine and infliximab. More recently the approach of combining medicine and surgery has offered greater success. Our own experience with infiximab and surgery has lead to the resolution of perianal fistulas in 68% of patients. We also found that the adding Seton placement to infiximab therapy decreased the rate of recurrent abscesses.
Others have found similar results; Topstad and colleagues (2003) found 67% of the 29 patients studied had a complete response to combination therapy and 19% had a partial response. In a comparative study by Regueiro and Mardini (2003), perianal fistulas were treated with infliximab alone versus combination therapy with Seton placement. The findings showed that initial response was improved with Seton placement (100% versus 82.6%), lower recurrence rates (44% versus 79%), and longer time to recurrence (13.5 months versus 3.6 months). The preceding chapter is on medical aspects of perianal disease treatment.
In our practice, after Seton placement, medical therapy is instituted to decrease the inflammatory process. Once the inflammation subsides, the Seton is down sized as the fistula fibroses and narrows in caliber, or it is removed.
A recent addition to our armamentaria is fibrin glue. Our technique is to place a noncutting Seton into the tract leaving it in place for 6 to 8 weeks. The Setons are removed and fibrin glue injected into the fistula tract. The internal opening is suture closed whereas the cutaneous one is left open. Lindsey and colleagues (2002) performed a randomized trial of fibrin glue versus conventional fistula treatment in patients with and without Crohn’s disease. One hundred percent of simple fistulas healed with standard treatment and only 33% healed with fibrin glue injection.
Of the complex fistulas, the cumulative healing rate after 1 to 2 treatments with fibrin glue was 69%. Sentovich (2003) reported on 48 patients with fistulas, among whom 10% were Crohn’s disease patients. The closure rate was 85%. Interestingly, the failure rate in their Crohn’s disease patients was only 20%. Over all, the healing rates of fistulas vary between 40% for Crohn’s disease patients and 80% for crypto glandular fistulas. Fibrin glue along with Seton placement may have a role to play in the treatment of complex perianal fistula with long tracts in patients with Crohn’s disease.
About 2% of women with Crohn’s disease will develop a rectovaginal fistula. Surgical as well as medical treatment maybe unnecessary as many of these fistulas are very low and have no associated symptoms. Surgical treatment is reserved for those patients with an unacceptable quality of life in whom medical treatment has failed. Unfortunately, the development of a rectovaginal fistula is a poor prognostic sign and may require proximal diversion to decrease local sepsis and/or eventual proctectomy. In patients undergoing rectovaginal fistula repair, the disease should be quiescent and the rectum distensible.
In general, for low rectovaginal fistula (< 15% of the sphincter involved) and normal sphincter function, simple fistulotomy is a viable option. However, some surgeons advocate use of an endorectal advancement flap as an alternative to fistulotomy or noncutting Setons in patients with a simple fistula who do not have active rectal inflammation. An advancement flap involves creating a flap of tissue around the internal opening of a fistula. Reports of its efficacy vary widely; in our experience, this approach yields unpredictable results.
Joo and colleagues (1998) reported sustained closure in 74% of 26 patients with fistulizing Crohn’s disease treated with endorectal advancement flap. Hull and Fazio (1997) reported that, among 35 patients with an advancement flap for low anovaginal fistulas, the initial healing rate was 54%, and an ultimate healing rate after > 1 procedure was 68%, but few others have such outcomes. Even more aggressive options can be considered in a few selective patients (Radcliffe et al, 1988; Halverson et al, 2001). Procedures such as an advancement sleeve flap can be used for larger perianal fistula disease, as long as the rectum is spared.
A report from Hull and Fazio (1997) looked at five patients with Crohn’s disease vaginal fistulas where four of the five have had resolution of their fistulas. Another 13 with complex fistulas have been treated in this manner, with 61 % having resolution of symptoms. Although these results seem reasonable, we are unable to achieve anything near these outcomes and do notperform flap advancement for patients with rectovaginal fistula caused by Crohn’s disease.
Influence of Proximal Disease
Does removal of proximal disease improve perianal disease in patients with Crohn’s disease? It has been shown that removal of all proximal disease does in fact promote healing in the perineum. Moreover, if proximal disease recurs, then the chance of recurrence in the perineum is also increased. Wolff and colleagues (1985) supported this conclusion with a report of 86 patients. In those patients with complete resection of proximal disease, only 29% developed recurrence. In those who had incomplete resections, 63% developed recurrent anorectal disease. However, in our opinion, proximal disease should be removed only when symptomatic as the influence of proximal resection or perineal disease is uncertain.