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Clinical and Endoscopic Diagnosis of IBD-Related Stricture, Fistula, and Abscess
List of Abbreviations
CD
Crohn's disease
CDAI
Crohn's Disease Activity Index
CT
Computed tomography
ECF
Enterocutaneous fistula
EEF
Enteroenteric fistula
EGD
Esophagogastroduodenoscopy
EUS
Endoscopic ultrasonography
GI
Gastrointestinal
IPAA
Ileal pouch-anal anastomosis
MRI
Magnetic resonance imaging
NSAID
Nonsteroidal antiinflammatory drugs
OCT
Optical coherence tomography
PVF
Pouch-vaginal fistula
RVF
Rectal vaginal fistula
TNF
Tumor necrosis factor
UC
Ulcerative colitis
US
Ultrasonography
VCE
Video capsule endoscopy
Introduction
Natural history of Crohn's disease (CD) has dictated that most patients would eventually develop various complications, namely stricture, fistula, and abscess, and colitis-associated neoplasia. Most patients with CD would need at least one bowel resection surgery during the disease course. Stricture, fistula, and abscess can occur after surgery, which may be related to postoperative complications or recurrence of CD. The same complications often occur in patients with ulcerative colitis (UC) who underwent restorative proctocolectomy and ileal pouch-anal anastomosis (IPAA). Again stricture, fistula, or abscess in UC patients undergoing IPAA may result from the development of de novo CD-like condition of the pouch or the postoperative complications.
Clinical history, physical examination, and laboratory tests are important for the diagnosis and management of stricture, fistula, and abscess. Although abdominal and pelvic imaging modalities have extensively been used to assess those IBD- or IBD surgery–associated complications, those diagnosis-only modalities have limitations, including high costs, exposure to radiation, a limited use in patients with renal insufficiency, and inconsistent reliability in distinguishing fibrotic from inflammatory strictures.
Endoscopy provides direct visualization of mucosal pattern and structure of bowel lumen. It can also deliver therapy, if amenable lesions are detected. Endoscopy is the main tool to assess the mucosal inflammation and colitis-associated neoplastic lesions for the diagnosis, differential diagnosis, disease monitoring, and dysplasia surveillance. However, the role of endoscopic evaluation in the diagnosis of stricture, fistula, and abscess has continuously being explored.
Stricture
Narrowed bowel lumen is common in patients with CD and in those with surgery. The causes of bowel lumen narrowing can be extrinsic and intrinsic. The extrinsic etiologies include adhesions and redundant bowel loop with angulation. The classic example is afferent limb syndrome in patients with IPAA, in which there is angulation between the afferent limb and pouch body. The intrinsic causes include strictures and intussusception. The stricture can further be divided into the primary, which is related to IBD disease or ischemia, and secondary, which is related to anastomosis or medicines (such as nonsteroidal antiinflammatory drugs [NSAIDs]). The diagnosis process for stricture should not only include the identification of its presence but also the assessment of number, location, degree, and associated conditions (such as fistula and abscess). Accurate diagnosis typically relies on a combined assessment of clinical, endoscopic, and radiographic (please see Chapter 7 ) features.
Clinical Assessment
Patients with stricture may or may not present with obstruction (complete or partial) or with symptoms. Classic symptomatology of stricture-related partial bowel obstruction includes nausea, vomiting, bloating, abdominal pain, constipation or obstipation, dyschezia, or sense of incomplete evacuation. History and physical examination are an important part of clinical evaluation. Patients may have postprandial bloating and pain, poor appetite, weight loss, and malnutrition. The predominant symptom and its degree are dependent on the degree, number, and location of strictures. For example, patients with distal rectal or anal stricture may mainly present with dyschezia, incomplete evacuation, and post-obstruction diarrhea. Patients with stricture at the ileocolonic anastomosis may present with bloating, nausea, and abdominal cramps.
We have noticed that the severity of symptoms and degree of stricture are poorly correlated, although this correlation has not been systemically studied. Confounding factors include coexisting functional bowel disease, small intestinal bacterial overgrowth, and patient's deconditioning due to long illness. The commonly used disease activity instruments, such as Crohn's Disease Activity Index and the Harvey–Bradshaw Index, were not specially designed for stricturing CD.
Conventional Endoscopy
Colonoscopy and esophagogastroduodenoscopy are the main tools for the evaluation of upper and lower gastrointestinal (GI) IBD. Other endoscopy modalities include push enteroscopy, balloon-assisted enteroscopy (see below), ileoscopy or colonoscopy via stoma, flexible sigmoidoscopy, and pouchoscopy. The main advantage of the conventional endoscopy is the direct visualization of diseased area and delivery of therapy if needed.
The degree of stricture can be empirically measured by the resistance at the passage of the scope and scored into mild, moderate, and severe, which is probably more accurate than radiographic measurement. Endoscopy can provide information on length and number of strictures, concurrent inflammation or ulcer in and around the strictures, and the presence of prestenotic bowel luminal dilatation. For severe stricture, which is not traversable to an endoscope, gentle antegrade balloon dilation or stricturotomy with needle knife may be needed. However, it is important for the endoscopist to distinguish the lumen of a tight stricture from a fistula opening. A preprocedure evaluation with abdominal and pelvic imaging is critical. In addition, the distinction can be made by spraying contrast through the orifice under fluoroscopy.
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