INTRODUCTION

Crohn’s disease (CD) is a common cause of perianal diseases. Perianal disease is a phenotype of CD, according to the Montreal Classification. Perianal CD may involve the pelvic floor muscles and rectum. Perianal or pararectal diseases can also occur after surgery of the distal bowel in inflammatory bowel disease (IBD) or other colorectal diseases. Clinically, antibiotics, immunomodulators, antitumor necrosis factor (TNF), antiintegrin agents, antiinterleukin (IL)12/IL23 agents, topical stem cell therapy, and hyperbaric oxygen therapy have been used to treat perianal fistula with varied efficacies. Endoscopic therapy may be attempted in some of these patients.

Perianal, pararectal, or parapouch fistulas or abscesses can also occur in patients after coloanal anastomosis (CCA), colorectal anastomosis (CRA) in benign or malignant disorders of the distal bowel, or ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC) or familial adenomatous polyposis, as long as there is anastomosis in the area. Contributing factors include obesity, cardiovascular comorbidities, mesenteric tension at the construction of anastomosis, pelvic radiation, and surgical expertise. While acute anastomotic leaks (AL) often result in abscesses and sepsis, chronic ALs can lead to the formation of sinus or fistula to adjacent organs or presacral, pararectal, parapouch, or perianal space or skin. Traditionally, percutaneous drainage with aspiration and placement of a catheter by an interventional radiologist ( Fig. 22.1A ) or colorectal surgeon ( Fig. 22.1B ) is the first-line treatment option for intraabdominal, pelvic, and perianal abscesses. Due to a high frequency of recurrence, risks and benefits of surgical resection and reanastomosis of ALs should be carefully balanced. Before the surgical reintervention, less invasive endoscopic therapy may be considered and attempted.

Drainage of abscesses. (A) Drainage of pararectal abscess with catheter by interventional radiology. (B) Drainage of perianal abscess with mushroom catheter by colorectal surgery.

Prior to the initiation of endoscopic therapy, it is important to delineate the anatomy and nature of the acute anastomotic separation, surrounding fluid collection, abscess formation, sinus, and fistula. A combined assessment of clinical, endoscopic, radiographic, and histopathological features is necessary. It is imperative to identify the location, number, length, and complexity of the sinus or fistula; the location, number, and size of associated abscess; concurrent bowel inflammation and stricture; and anatomy and status of adjacent organs. Previous endoscopy and operative reports should be reviewed. Common endoscopic techniques for perianal fistulas and abscesses are incision and drainage of perianal abscess ( Fig. 22.2A – C ), endoscopic fistulotomy ( Fig. 22.3A – C ), endoscopic placement of vacuum sponge or pigtail stent through AL, endoscopy-guided seton placement ( Fig. 22.4A – C ), endoscopic administration of sclerosing agents (such as mixed hypertonic glucose and doxycycline) ( Fig. 22.5A and B ), ^, or topical stem or stromal cells ( Fig. 22.6 ). Attempts to close the internal fistular opening in CD or chronic ALs often fail.

Endoscopic incision and drainage perianal abscess in Crohn’s disease. (A) Perianal abscesses with seton. (B) Seton seen at the anal canal to the internal orifice of the perianal fistula. (C) Status post endoscopic needle-knife incision of the abscess.

Endoscopic fistulotomy. (A) Perianal fistula and abscess in Crohn’s disease with previously placed seton. (B) Endoscopic fistulotomy with a needle knife after topical application of betadine and injection of lidocaine. (C) Postprocedure appearance.

Endoscopy-guided placement of seton. (A) Perianal fistula tract probed and detected with a guidewire through the external orifice. (B) Internal orifice of the fistula visualized at the anal canal. (C) A seton introduced with the guidewire.

Endoscopic injection. (A) Perianal fistula tract detected with a guidewire. (B) Endoscopic injection of mixed hypertonic glucose and doxycycline through the internal orifice with a catheter.

Appearance of stem cell therapy for perianal fistula in ileal pouch-anal anastomosis.

In this chapter, we discuss endoscopic therapy in pararectal, parapouch, and perianal fistulas and abscesses associated with CD, leaks at IPAA, or CRA.

ENDOSCOPIC THERAPY FOR PERIANAL CROHN’S DISEASE

Multiple classifications have been proposed to characterize perianal CD. One instrument classifies fistulas as either “high” or “low” relative to their presence above or below the dentate line. Parks’ classification uses the external anal sphincter to identify five main groups of fistulas: intersphinteric, transsphincteric, suprasphincteric, extrasphincteric, and superficial.

The internal orifice of the perianal fistula may be visualized by a careful endoscopy via the anus ( Fig. 22.7 ). The endoscopist may have the temptation to close the internal orifice with clips or sutures. However, there are scant published data on the use of through-the-scope clips (TTSC) or over-the-scope clips (OTSC) for the treatment of perianal fistulas. In a retrospective single-center study of 10 cases with refractory anal fistulas, including 6 patients with underlying CD, the investigators reported a technical success of OTSC in all patients with the permanent closure of fistula in 7 patients (70%) in a median time of follow-up of 72 days. In clinical practice, endoscopic closure of primary, lower (at or close to the dentate one), CD-associated fistulas, including perianal fistula, hardly works. It may carry a significant risk for morbidities, including worsening of the fistula and formation of abscesses. However, endoscopic closure with TTSC, OTSC, or endoscopic stitch device may be attempted for high, colorectal anastomosis-associated perirectal or perianal abscess.

Internal orifice of perianal fistula originating from the dentate line.

Perianal CD often coexists with anorectal ring (ARR) strictures, i.e., the strictures at the squamous-columnar epithelial junction. Whether the ARR strictures are the cause or the result of the perianal disease is unknown ( Fig. 22.8A – C ). This author has summarized the natural history of luminal CD at the distal ileum as follows: “no inflammation, no stricture; no stricture, no fistula; and no fistula, no abscess.” The classic example is chronic inflammation at the terminal ileum and ileocecal valve resulting in stricture at the valve, prestenotic dilation of the proximal bowel lumen, and subsequent ileocecal, ileo-ileal, ileosigmoid fistulas, and abscess formation. The orientation of the inflammation-stricture-fistula is characterized by the presence of a downstream stricture associated with an internal orifice of the fistula tract at the ileum proximal to the stricture. The orientation of ARR strictures and perianal fistulas and abscesses, on the other hand, is opposite, that is, the stricture coexists with downstream fistulas and abscesses in the perianal region. ARR strictures are likely a contributing factor to the formation of cryptoglandular fistulas to the perianal region, prostate, or vagina. This author routinely treats ARR strictures with endoscopic stricturotomy using an insulated-tip knife or needle-knife and notices the improvement in symptoms of pelvic outlet obstruction and perianal fistula drainage of the endoscopic stricture therapy ( Fig. 22.8A – C ).

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