by Gervaz Pascal, Wexner SD.
Anorectal infection and sepsis are common challenging problems. Although often used synonymously, sepsis and infection are different. Sepsis are the systemic responses to local infection, including hyperthermia, tachycardia, tachypnea, hypotension and altered mental status. Fortunately, most patients with infectious anorectal diseases present with a localized abscess or fistula, without systemic toxicity. Regarding severe anorectal sepsis, two distinct entities will be considered: Primary anorectal sepsis refers to bacterial invasion of the soft tissues in the peri-anal area, which is most commonly associated with Crohn's disease (CD) and immunocompromise. Secondary anorectal sepsis results from dehiscence of a pelvic anastomosis after restorative proctocolectomy or low rectal resection. This chapter will review the therapeutic options and discuss the currently controversial issues surrounding the management of anorectal sepsis in patients with CD, AIDS and hematologic diseases. Additional emphasis will be placed on the prevention and management of sepsis related to a leaked pelvic anastomosis. A Medline search was conducted and all relevant articles published since 1994 in the English language were analyzed. Subsequently, randomized trials and meta-analyses were critically reviewed to establish current therapy guidelines supported by evidence-based data. Complicated anorectal sepsis is defined as the systemic response to an infection originating from the lower alimentary tract, distal to the peritoneal reflection.
Anorectal sepsis in Crohn's disease
The perineal manifestations of Crohn's disease include fistula, abscess, fissure, ulcer, stenosis and skin tags. They are more frequently associated with colonic than with either ileocolic or jejunoileal disease. Although incision and drainage of abscesses is commonly performed to alleviate symptoms, a conservative nonoperative approach has traditionally been advocated for the management of peri-anal fistulas complicating CD. This preference emanated from fear of impaired wound healing after surgery. However, more recently, a paradigm shift has occurred in which many surgeons perform advancement flap and fistulotomy procedures for these fistulas. The following paragraph will review the new information which has allowed this attitude adjustment.
Cytokines play a central role in the pathogenesis of inflammatory bowel disease and recently Tumor-Necrosis Factor alpha (TNFα)4 has been identified as target molecule for immune intervention in chronic active CD. Two preliminary randomized, placebo-controlled trials have demonstrated that anti-TNFα monoclonal antibody treatment (infliximab) reduces clinical signs and symptoms in patients with active CD. Although both studies were relatively small in the larger one, 90% of 108 patients had peri-anal fistulas. A clinical response (closure of fistula) was achieved in 54 (68%) of the 83 patients treated with infliximab vs. 4 (17%) out of 24 patients in the placebo group. Accordingly, in August 1998, infliximab received FDA approval for the treatment of patients with severe fistulizing perineal CD who do not respond to conventional medical therapies. Repeated administration maintains remission, although long-term safety is still a cause of concern. Infliximab 5 mg/kg should be considered in CD patients with complicated peri-anal fistulas and/or delayed perineal wound healing refractory to conventional medical management.
Peri-anal fistulous complications occur in 10–25% of patients with CD. As previously noted in this chapter, there has been a recent shift towards more aggressive management of patients with CD and anal fistulas. Any surgical procedure for anal fistula should be preceded by a thorough identification of its components, namely internal and external openings, primary and secondary tracts, and by an assessment of the patient's continence. Placement of drainage catheters and noncutting setons, advancement flap closure of fistulas and selective construction of diverting stomas are preferred options which may postpone or even obviate the need for proctectomy and permanent stoma. One multicenter study investigated the outcome of surgery for peri-anal CD: while medical treatment was curative in 17% of 123 cases, 97 out of 166 (58%) patients who underwent anal surgery had a “positive” outcome. However, recurrence of anal disease requiring further surgery occurred in 24% of cases.
The use of draining setons has proven effective in the treatment of complex high transsphincteric and complex anal fistula and sepsis related to CD. Faucheron et al. reported a series of 41 patients with CD who underwent long-term seton drainage for high fistula. Twelfe percent of patients required subsequent proctectomy for severe proctitis, 12% developed incontinence and 20% had a recurrence. McCourtney and Finlay cured 96% of fistulas with a seton technique designed to avoid open drainage of the intersphincteric space and thus to preserve the internal sphincter. However, even with this tissue-preserving method, 3 out of 4 patients with CD underwent subsequent proctectomy because of severe rectal involvement. Fistulotomy probably has the highest cure rate, but also has the greatest chance to impair fecal continence. Cutting setons carry the same risk-benefit profile. While drainage setons have no risk of sphincter compromise, they do not eradicate the tract. Like drainage setons, flaps do not entail muscular division, but have a high level of complexity and, accordingly, failure.
Endorectal advancement flaps are generally not useful for patients with either severe proctitis or active sepsis. The flap consists of mucosa, submucosa and some fibers from the internal anal sphincter muscle. It should be rhomboid-shaped, tension-free, thick and well-vascularized. Because sepsis is a major cause of failure, full mechanical and antibiotic bowel preparation are preoperatively administered. In our experience, the major cause of failure is often the presence of concomitant small bowel CD.
In summary, it must be emphasized that surgery alone cannot offer a definitive cure for CD. However, it will provide symptomatic relief in all patients with abscesses and in some patients with complex fistulas. Since peri-anal complications are manifestations of the underlying inflammatory bowel disease, the addition of immunomodulation therapy, possibly with anti-TNFα monoclonal antibody, may, in the near future, improve the results of surgical treatment of anorectal CD. Abscesses should be drained, while simple low transsphincteric and intersphincteric fistulas can be treated by sphincterotomy. Drainage setons rather than cutting setons should be used to resolve acute sepsis and limit recurrence and, or progression of disease. They may also be used as preparation for advancement flap closure of high transsphincteric or suprasphincteric fistulas. However, flaps should only be undertaken in the absence of significant rectal inflammation.
Prospective trials should be conducted to assess the role of adjuvant immunotherapy with infliximab in promoting wound healing after surgical treatment of complex and high transsphincteric fistulas in CD patients.
Anorectal sepsis in AIDS
Anorectal disease is commonly found in homosexual and bisexual male HIV-seropositive patients. The spectrum of conditions encompasses both common benign anorectal pathologies such as hemorroids, ulcers, condylomata acuminata and perianal sepsis, and both benign and malignant HIV-related conditions including anal lymphoma. These disorders can be complex and difficult to treat. The microbiology of HIV-related septic anorectal disease was documented by Goldberg et al. Forty-seven patients thought to have an infectious process were prospectively studied using a standardized multiculture protocol. Surprisingly, only 68% of them had positive cultures including most commonly Herpes simplex, Cytomegalovirus, Neisseira gonorrhoea and Chlamydia. However, the true incidence may have been higher assuming that organisms such as Cryptococcus are difficult to detect by culture.
In a recent large series, Barrett et al. have reported 485 procedures performed on 178 patients (mean of 2.7 per patient). Recent data have suggested that wound healing and the ultimate results of surgery have been improved by better medical management of HIV infection. Despite enhanced immunomodulation therapy, delayed wound healing remains a significant problem after such procedures, which may be correlated with preoperative CD4+ lymphocyte count. In summary, the best management of anorectal disease in HIV-infected patients is still unclear, but invasive procedures should be avoided whenever the CD4+ lymphocyte count is less than 50 cells/microL. If a procedure is to be performed, aggressive preoperative identification of specific pathogens allows more directed antibiotic therapy. Finally, optimal medical management of HIV infection is required in order to achieve better surgical results and to reduce the risk of delayed wound healing. Optimal immune function should be insured; using this protocol, simple benign conditions in immunologically optimized patients can be treated as in the standard population with similar expectations of a satisfactory outcome. However, advanced malignancies and complex sepsis, particularly in severely compromised patients, augur for a poor outcome. Relative to sepsis, abscesses should always be drained; liberal use of drainage rather than cutting setons and fistulotomies are advisable. Fistulotomies are only undertaken for the simplest intersphincteric and low transsphincteric fistulas. Flaps are virtually never indicated.
Anorectal sepsis in patients with hematologic diseases
Anorectal sepsis affects 5–7% of hospitalized leukemic patients and represents a major cause of mortality. Bacteremia and septic shock have been observed in leukemic patients with perianal abcesses. Grewal et al. have compared operative and nonoperative management of these patients and concluded that anorectal abcesses in neutropenic leukemic patients may be safely drained; however, the mortality was identical in both groups, averaging 20%. The neutrophil count is an important prognostic factor; severely neutropenic patients are prone to develop indurations without fluctuance and should be nonoperatively managed, whereas leukemic patients with borderline neutrophil counts may present with fluctuant lesions amenable to surgical drainage. Nonoperative treatment often includes parenteral antibiotics and radiation therapy.
Postoperative anorectal sepsis
During the last decade, colo-anal and ileo-anal anastomoses have become more commonly performed in order to preserve anal sphincter function. These efforts to restore intestinal continuity are associated with significant morbidity including anastomotic complications. While the incidence of intraperitoneal anastomotic dehiscence in most studies does not exceed 5%, the leak rate after procedures involving anastomoses in the lower 3–5 cm of the rectum is reported in between 8–20%, regardless of the anastomotic technique.
The clinical presentation of pelvic anastomotic dehiscence is variable; in a significant number of cases, patients with radiologically demonstrated leaks remain asymptomatic. However, deterioration of a patient's general condition with pyrexia and diarrhea 3 to 6 days after surgery should raise a high index of suspicion. CT scan and gastrograffin enemas are useful to demonstrate extravasation of contrast and reveal the presence and location of abscess.
Since sepsis due to anastomotic dehiscence is one of the most dramatic complications of pelvic surgery, its prevention has attracted considerable attention. Currently, many surgeons use a diverting stoma after lower rectal resection. Although proximal fecal diversion will not prevent the leak, its role is to minimize the adverse sequelae of the leak. In patients with ulcerative colitis after restorative proctocolectomy, sepsis is the leading cause of both pouch failure and poor functional outcome. However, the routine use of a diverting stoma is still a matter of debate, because there is a higher incidence of postoperative small bowel obstruction after ileostomy construction. Moreover, even in the absence of stoma-related complications, further surgery necessitating increased hospitalization, convalescence, and cost, ensue.
It has been recently demonstrated that, in patients with mid rectal cancer (6 to 11 cm from the anal verge), the use of a protective defunctioning stoma significantly decreased the risk of clinical anastomotic leak and sepsis following low colorectal anastomosis. Similarly, in a series of 100 patients with ulcerative colitis who underwent restorative proctocolectomy with or without defunctioning ileostomy, Williamson et al. reported an increased incidence of pelvic sepsis, reoperation and life-threatening complications in the group without temporary ileostomy. Hallbook et al. reported a significantly lower rate of anastomotic leak after colonic J-pouch than after straight coloanal anastomosis for the treatment of midrectal carcinoma. Thus, there is evidence that surgical procedures involving low pelvic anastomoses carry a high risk for anastomotic leak and septic complications and should be routinely performed with a proximal defunctioning stoma. The risk may also be decreased in patients with midrectal tumors by constructing a colonic J-pouch. The role of omentoplasty in the prevention of anastomotic leakage after colonic or rectal resection has been investigated by the French Association for Surgical Research. In a series of 701 patients, there was no indication that omentoplasty decreased the incidence or the severity of anastomotic failure.
The issue of the technical options to perform low colo-anal or ileo-anal anastomosis and comparison of their respective leak rates is debatable. Handsewn anastomoses have been generally superceded by stapling on the basis of facilitating the operation and avoiding over-dilatation of the anal sphincter. Zivio et al. have recently reported their results in a large series of ileo-pouch-anal anastomosis. The incidence of sepsis and pouch complications was higher after the handsewn technique. The stapled technique allows a lower level of anastomosis and therefore increases the opportunity for sphincter preservation. This technique is clearly superior for ileo-anal anastomosis and is also probably better for colo-anal anastomosis. However, for colorectal anastomosis, the staplers may have a higher incidence of stricture than do handsewn anastomoses. Should Nevertheless a leak occur, the presence of a pelvic drain placed at the time of surgery may prevent spreading sepsis and divert the infection along a drain tract, creating an artificial enterocutaneous fistula. However, this opinion has been challenged, because premature removal of drains in many cases (48–72 hours after surgery) is unlikely to prevent sepsis related to anastomotic dehiscence (which may occur 4 to 6 days after the procedure). A prospective randomized study investigated the role of postoperative irrigation/suction drainage after low rectal resection and failed to demonstrate any advantage of this procedure on the development of pelvic sepsis. Another group reached the same conclusion in a smaller study where patients who underwent rectal resection with or without drainage had the same incidence of complications. Thus, although some surgeons continue to advocate routine use of drains after pelvic anastomosis, there is little evidence-based data to support this practice. Control of sepsis is the cornerstone of successful management of the leaked pelvic intestinal anastomosis. Obviously, proximal diversion is the best option whenever gross fecal contamination has occurred. In many cases, however, stoma creation is not required.
In: Holzheimer RG, Mannick JA (Eds).
Surgical treatment-Evidence-Based and Problem-Oriented
W. Zuckschwerdt Verlag Munchen (2001):pp. 240-246