Introduction

Fistula and abscess can result from underlying Crohn’s disease (CD) or ulcerative colitis (UC) or from CD- or UC-related surgery. Fistula and abscess represent the most advanced phenotypes of CD, as compared with inflammatory or fibrostenotic counterparts of the disease, which has a great impact on the disease outcome and patient’s general wellbeing and quality of life. In a majority of patients with CD, fistula results from persistent mucosal and transmural inflammation and stricture, which is evidenced by longitudinal studies and clinical coexistence of inflammation, stricture, and fistula in a given patient. Medical therapy, including the use of antibiotics, immunomodulators, antitumor necrosis factor (TNF), anti-integrins, or anti-interleukin (IL)12/IL23 agents, has been showed to be effective in reducing fistula drainage, particularly in the presence of concurrent bowel inflammation. However, it appears that the efficacy of medical therapy is limited to perianal fistulas and to a much less extent, enterocutaneous fistula (ECF). It is generally believed that the medical therapy has a limited role in the treatment of hollow organ-to-hollow organ fistulae, such as rectal bladder fistula, rectal-vaginal fistula (RVF), pouch-vaginal fistula (PVF), enteroenteric fistula (EEF), and gastrocolonic fistula from CD. Currently, the standard treatment of those hollow organ-to-hollow organ fistulae is surgical intervention. The main disadvantages of surgical treatment are its invasiveness and complexity, postoperative infectious and technique-associated complications, limited efficacy, and frequent postoperative disease recurrence. Surgery in patients with inflammatory bowel disease (IBD) carries a higher risk for the development of stricture, anastomotic leak, sinus, fistula, and abscess, than that for non-IBD colorectal diseases. In addition, the distinction between disease-associated complications and surgery-related complications can be difficulty, as the two situations can present with similar clinical, endoscopic, and radiographic features.

For the last decade, endoscopic therapy has evolved to a valid option for the treatment of IBD. Endoscopic balloon dilation (EBD) has become a part of routine clinical practice in the treatment of IBD-associated or IBD surgery–associated strictures. The role of endoscopic therapy for CD fistula and IBD surgery-related fistula has also been explored, despite the fact that the application of endoscopic therapy to IBD lags behind that for diseases of the upper gastrointestinal (GI)_track and pancreaticobiliary system. The gap in endoscopic therapy in IBD may attribute to the lack of deep knowledge and interest in disease process and management of IBD from therapeutic endoscopists and/or the lack of technical skills in advanced endoscopy from the IBD specialists. There is a growing need for endoscopic management of IBD, as the latter has become an integral part of multidisciplinary approach to this complex disorder in major tertiary-care centers ( Table 16.1 ).

Principles of Endosocpic Treatment of Fistula, Sinus, and Abscess

General principles of therapeutic endoscopy in IBD are discussed in a separate chapter ( Chapter 10 ). Like any management plan for any disease, the successful treatment relies on the knowledge of principles, the development of techniques by the implementation of the principles and the proper use of tools, devices, and equipment. Therefore, the doctrine should be “principle first, technique second, and tools, device, and equipment last.”

We should have a solid knowledge in pathogenesis, disease process, and natural history of IBD. This author has summarized the natural history of CD as follows: “no inflammation, no stricture; no stricture, no fistula; and no fistula, no abscess.” This leads to proper approaches to various conditions in IBD. We should understand the advantages and disadvantages of medical versus endoscopic versus surgical therapies. The goals of the current medical treatment for CD have been the control inflammation and prevention of development of stricture and subsequent fistula and abscess and postoperative disease recurrence. The main goals of surgical treatment in CD are the relief of mechanical obstruction, repair or removal of fistula, and drainage of abscess. Generally speaking, medical therapy for IBD is less effective and also less invasive than surgical therapy, and vice versa. The “happy median” is the endoscopic therapy.

Endoscopic therapy is less invasive than surgery and may be more effective than medical therapy, especially for IBD-associated stricture. The endoscopic therapy plays a role in bridging and facilitating the efficacy medical and surgical therapy. As endoscopists, we should get the first-hand knowledge of mechanical complication of IBD, by observing surgical procedure in operating room (OR) and participation in the examination of histopathology of bowel resection specimens with our pathologists and surgeons. We should understand indications, contraindications, and limitations of endoscopic therapy for IBD. When we deliver endoscopic therapy for IBD-associated fistula and abscess, we should also address concurrent bowel inflammation with proper medical therapy and concurrent strictures with EBD or endoscopic stricturotomy. Concurrent intraabdominal or perianal abscess may be treated with radiographic, endoscopic, or surgical drainage.

Fistula and abscess often result from underlying CD or UC or from IBD-associated surgery. Before the initiation of medical, endoscopic, or surgical therapy, it is important to delineate the anatomy and nature of fistula and abscess. A combined assessment of clinical, endoscopic, radiographic, histopathological features is required. It is important to evaluate the location, number, length, complexity of fistula; the number, size, and associated abscess; and concurrent bowel inflammation and stricture. We should carefully review previous operative report(s). The interaction and collaboration with GI pathologist, GI radiologists, and surgeons is critical, especially for complex cases.

The main principles for the endoscopic management for fistula are to (1) open up the fistula track, that is, fistulotomy, whenever possible; (2) close the primary opening of the fistula and keep the secondary opening; (3) fill up or inject the fistula track with various agents, such as stem cells, fibrin glue, or plug, if possible. We need to make sure that the closure of the primary opening of a fistula should precede the closure of the secondary opening or at least the primary and secondary openings are closed the same time. If the sequence is reversed, that is, the closure of the secondary opening prior to the closure of the primary opening, the patient may develop abscess or branching of a simple fistula track into complex tracks. The outcomes can be measured by a complete or partial closure of the primary and/or secondary openings, absence of fistula drainage, complete scarring off of fistula track, and prevention from the formation of abscess or branched fistula.

Those principles have helped to develop and implement proper techniques of endoscopic therapy for IBD-associated fistula, sinus, and abscess, and for IBD-surgery–associated fistula, suture line, or anastomotic leaks or abscess.

Endoscopic Fistulotomy

Endoscopic fistulotomy may be defined as the one performed with the use of an endoscope or performed in the endoscopy unit with an endoscopic device. For any fistula, complete fistulotomy provides the best outcome as compared with other means of fistula treatment. However, not all the fistulae are amenable to endoscopic fistulotomy. Endoscopic fistulotomy may be attempted in following conditions: (1) suture line or anastomotic leak in the distal bowel, leading to bowel-bowel fistula; and (2) the track should be superficial and short. The short fistula in the distal bowel is often associated with prior surgery in the area, such as ileal pouch-anal anastomosis (IPAA), coloanal anastomosis, and colorectal anastomosis. It is important to measure the length of fistula track and thickness of overlaying bowel wall, by procedural abdominal imaging as well as a soft-tip guidewire via endoscopy. This author has gained some experience in endoscopic fistulotomy in patients with distal bowel-to-distal bowel fistula, including ileal pouch-to-pouch fistula. Deeper fistula track which undergoes endoscopic fistulotomy may need the deployment of endoclips along the electroincised edges of the fistula track to prevent the reformation of the track ( Fig. 16.1 ).

Endoscopic fistulotomy at ileocolonic anastomosis in Crohn’s disease. (A) Fistula opening at the distal neoterminal ileum; (B) fistula track ( green dotted line ) from the neoterminal ileum to proximal colon detected by a guidewire; (C) needle-knife fistulotomy; (D) clipping of edges of the incised bowel wall to prevent reformation of the fistula.

Shen B. Gastrointest Endosc 2017; 85 :1133–43.

Endoscopic treatment of perianal fistula may be more complicated. Complete fistulotomy can be safely performed in patients with superficial perianal fistula outside the external sphincter, that is, extrasphincteric fistula ( Fig. 16.2 ). Partial fistulotomy may be performed in patients with a long perianal fistula with the secondary orifice located way beyond the edge of external anal sphincter ( Fig. 16.3 ). Fistulotomy with endoscopic needle knife or isolated-tip knife with proper topical anesthesia has the obvious advantage over surgical scalpel knife with minimum bleeding of the former approach.

Endoscopic fistulotomy of an extrasphincteric perianal fistula in Crohn’s disease. (A) A newly developed fistula track ( green dotted line ) despite seton treatment; (B) postprocedure view of needle-knife fistulotomy.

Shen B. Gastrointest Endosc . 2017; 85 :1133–43.

Treatment of perianal abscess/fistula in endoscopy suite: (A) Endoscopic needle knife ( red arrow ) was used to drain the abscess ( green arrow ) and deliver fistulotomy; (B) postprocedure view.

Shen B. Gastrointest Endosc . 2017; 85 :1133–43.

Endoscopic fistulotomy can be used in combination with other endoscopic treatment modalities, such as closure of suture line leak ( Fig. 16.4 ), stricture dilation, and needle-knife stricturotomy.

Endoscopic fistulotomy and closure of the tip of the J pouch leak. Seton placement in perianal fistula. (A) A fistula track ( green dotted line ) near the tip of the “J” leak; (B) complete endoscopic needle-knife fistulotomy with placements of endoclips; (C) the tip of the “J” leak detected with a guidewire; (D) deployment of an over-the-scope clip to close the leak.

Endoscopic Sinusotomy

Anastomotic leak is common in surgery for CD and UC. The leak can be acute and chronic. Acute anastomotic leak can cause abdominal and pelvic sepsis. Acute leak can be managed medically, endoscopically, and surgically (see below). Chronic anastomotic leak can form a sinus cavity. The most common location of sinus is the presacral area, which has been reported often in IPAA surgery. Pouch sinus is defined as a blind tract resulting from chronic pouch-anal anastomotic leak or suture/staple line leak. It occurs in 2.8%–8% of IPAA patients. Most patients required surgical intervention with incision and drainage, debridement, unroofing, occlusive treatment with fibrin glue, pouch diversion, or surgically redo pouch.

We developed novel endoscopic needle-knife sinusotomy (NKSi) to treat the pouch sinus with remarkable outcome. We reported of the first cohort of 65 patients, with the mean depth of the pouch sinus was 4.4 ± 1.8 cm. Twenty patients (30.8%) had complex pouch sinuses. After a median of 2.0 needle-knife therapies (interquartile range [IQR]: 1.5–3.5) during a follow-up period of 1.1 years (IQR: 0.4–2.8), 28 patients (43.1%) with pouch sinus had complete healing, 27 (41.5%) had a partial healing. The risk of complication was low. The principle of endoscopic NKSi is the incision of the wall of posterior pouch body next to the sinus, making the latter become a part of pouch and eventual epithelialization of sinus cavity. The key of success of the procedure is the deployment of endoclips along the incised edges of the sinus ( Fig. 16.5 ).

Endoscopic needle-knife sinusotomy. (A) A presacral sinus with pus ( green arrow ); (B) complete sinusotomy with needle knife; (C and D) placement of endoclips along the incised edges of sinus.

Endoscopic Injection of Filling Agents

Various agents have been used to fill the track of to inject to the wall of perianal fistula in IBD or non-IBD patients. The procedure is normally performed in a combination with examination under anesthesia (EUA) in OR by colorectal surgeons. Theoretically, the administration of these agents into the fistula track can be achieved via endoscopy.