Endoscopy of the small bowel in inflammatory bowel disease

Endoscopy of the small bowel in inflammatory bowel disease

Gastrointest Endoscopy Clin N Am 12 (2002) 485 – 493 Endoscopy of the small bowel in inflammatory bowel disease Scott D. Lee, MDa, Russell D. Cohen, ...

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Gastrointest Endoscopy Clin N Am 12 (2002) 485 – 493

Endoscopy of the small bowel in inflammatory bowel disease Scott D. Lee, MDa, Russell D. Cohen, MDb,* a

University of Washington School of Medicine, 1959 North East Pacific Avenue, Box 356424, University of Washington Medical Center, Division of Gastroenterology, Seattle, WA 98195, USA b The University of Chicago Medical Center, MC 4076, 5841 S. Maryland Avenue, Chicago, IL 60637, USA

The diagnosis of small bowel inflammatory bowel disease has traditionally relied upon radiographic methods, as the evaluation of the small bowel extending from beyond the proximal jejunum to all but the very distal terminal ileum has been out of reach of traditional endoscopes. Endoscopic treatment of small bowel bleeding sources and dilation of strictures has likewise been limited. The gastroenterologist has typically relied upon radiographic visualization and surgical therapies for the vast majority of these patients. The advent of small bowel endoscopy allows for direct visualization, and sometimes biopsy, of the small bowel, confirming the diagnosis and extent of involvement with disease. Some of the new technologies allow for endoscopic treatment of bleeding sources, and dilation of small bowel strictures. This article will introduce four of the endoscopic techniques currently available for evaluating small intestinal involvement in inflammatory bowel disease: Sonde Endoscopy, Push Enteroscopy, Intraoperative Endoscopy, and Capsule Endoscopy. The applications and limitations of each of these techniques will be discussed, as well as a glimpse into the future of small bowel endoscopy. The role of small bowel endoscopy in the diagnosis of, and endoscopic therapy in the treatment of, inflammatory bowel disease will be reviewed. The introduction of endoscopic evaluation of the bowels in patients with inflammatory bowel disease (IBD), Crohn’s disease, and ulcerative colitis has resulted in a gradual shift from the radiologist to the gastroenterologist for the diagnosis of disease. One exception has traditionally been Crohn’s disease limited to the small bowel. While Crohn’s disease (CD) has been described in all parts of the gastrointestinal tract, from mouth to anus, the small intestine is involved in up to 70% of patients [1], with 30% having small bowel disease alone. In contrast, * Corresponding author. E-mail address: [email protected] (R.D. Cohen). 1052-5157/02/$ – see front matter D 2002, Elsevier Science (USA). All rights reserved. PII: S 1 0 5 2 - 5 1 5 7 ( 0 2 ) 0 0 0 0 8 - 9

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involvement of the upper gastrointestinal tract was previously thought to be uncommon, occurring in only 5% [2,3]. However, prospective studies have suggested that the prevalence of Crohn’s of the upper gastrointestinal tract is higher than previously reported, as many patients may have asymptomatic disease [4]. It is likely that some patients with mild small bowel disease might be asymptomatic as well. Endoscopic evaluation of the human small bowel is compromised by the fact that the mid to distal jejunum and most of the ileum has traditionally been out of reach of even the most advanced endoscopes, resulting in evaluations of those areas being delegated to the small bowel radiologist. These studies are notoriously operator-dependent, and subtle mucosal changes may be difficult to detect, especially given the propensity of Crohn’s to ‘‘skip around’’ in some patients with Crohn’s. The gastroenterologists’ frustrations may soon come to an end. Recent advances in technology have for the first time raised the potential of endoscopic visualization of the entire small bowel. Currently there are four endoscopic techniques available for evaluating small intestinal involvement in IBD: Sonde endoscopy, push enteroscopy, intraoperative endoscopy, and capsule endoscopy. This article will discuss the utility of these techniques in the diagnosis and management of small bowel (defined as distal to the Ligament of Treitz) inflammatory bowel disease (Table 1).

Diagnosis The initial presentation of small bowel Crohn’s disease is highly variable based on the location and length of involvement. As a result, Crohn’s disease can be difficult to diagnose, as reflected in its longer prodromal period than ulcerative colitis [5]. Small bowel endoscopy has the potential to play an integral role in differentiating Crohn’s from other etiologies that may present with similar clinical presentation. Lesions due to ischemia, radiation, neoplasm, infection, and drugs (ie, antibiotics, nonsteroidal anti-inflammatory drugs), must be considered in the appropriate clinical setting. These diseases, unfortunately, can be nearly indistinguishable radiographically from Crohn’s disease. Although there are not specific Table 1 Comparison of four different modes of small bowel endoscopy

Level of invasiveness View entire small bowel Obtain biopsies Perform therapy Contraindications a

Sonde endoscopy

Push enteroscopy

Intraoperative enteroscopy

Capsule endoscopy

++ yes no no None

+++ no yes yes Sedation intolerance

++++ yes yes yes Inability to tolerate surgery or anesthesia

+ yes no no Bowel obstruction or AICDa

Automatic implantable cardiac defibrillator.

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endoscopic lesions pathognomonic for Crohn’s, certain endoscopic appearances can be highly suggestive of IBD. Confirmation of the diagnosis by endoscopic biopsy is also possible in some instances. Sonde enteroscopy Sonde enteroscopes have a working length of 250 – 400 cm. In 83% of patients undergoing Sonde endoscopy, the endoscope can be passed to the mid or distal ileum [6]. The passage time takes on average 4.3 hours. The primary utility for Sonde enteroscopy has been in evaluating sources of obscure gastrointestinal bleeding. It is not possible to obtain biopsies with Sonde enteroscopy, and because of the time-consuming nature of the procedure it is rarely performed. One publication using intraoperative Sonde enteroscopy for sources of obscure bleeding in 16 patients found that six of the patients had changes consistent with Crohn’s disease, affecting the management of these patients [7]. Although Sonde enteroscopy has been a useful diagnostic tool in the past, with current technology (see below) there are few situations in which Sonde enteroscopy would be preferable to either capsule enteroscopy or intraoperative enteroscopy with a push enteroscope. With the advent of capsule endoscopy, it is likely that Sonde enteroscopy in its current state will be relegated to historical reference. Push enteroscopy The primary utility of push enteroscopy is to evaluate for etiologies of occult gastrointestinal bleeding [8]. It is also used for evaluation of the small intestine when patients are suspected of having small intestinal Crohn’s undetectable by normal radiographic studies, or when biopsies are desired. Currently standard enteroscopes are 210– 220 cm in length, and have a standard or therapeutic sized working channel (Fig. 1). On average, with the use of an overtube, it is possible to examine and obtain biopsies up to 100 cm beyond the Ligament of Treitz [9]. When evaluating for small intestinal involvement in Crohn’s disease, biopsies

Fig. 1. Pentax Enteroscope with 3.5-mm working channel. Working length 220 cm, field of view 120° (photograph courtesy of Pentax Corporation, Englewood, CO).

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should always be taken of even normal-appearing mucosa, as there can be histologic activity even when the mucosa appears macroscopically normal. When used to evaluate patients who were suspected of having Crohn’s disease, push enteroscopy was able to identify lesions in the small intestine consistent with Crohn’s in 50% of the patients evaluated [10]. Of the eight patients studied, five were adults with chronic diarrhea and abdominal pain, and three were children with growth retardation and weight loss associated with diarrhea. Four patients were found to have macroscopic and/or microscopic lesions consistent with Crohn’s disease in the small intestine, which was undetected by other standard endoscopic and radiologic studies. Although standard push enteroscopy allows evaluation beyond the ligament of Treitz, it does not allow complete visualization of the small intestine. Recently, there has been a report of total enteroscopy to the ileocecal valve using a steerable double balloon push enteroscope [11]. The utility and feasibility of this new endoscopic technique for visualization alone will need to be contrasted with capsule endoscopy, but biopsies from all segments of the small intestine are possible with this new technology. This new technology may allow more complete evaluation than standard push enteroscopy, and is less invasive than intraoperative enteroscopy. Intraoperative enteroscopy Advances in laproscopic surgical techniques have reduced the invasiveness of total intraoperative enteroscopy, allowing them to be performed through small enterotomies safely [12]. This approach involves the manual advancement of the small intestine over the enteroscope by the surgeon, while the endoscopist evaluates the mucosa from the luminal side. Although enteroclysis is sensitive for evaluating changes of Crohn’s disease in the small intestine [13], intraoperative enteroscopy is better at evaluating small changes, including ulcers and inflammatory polyps [14]. In one study using total intraoperative enteroscopy, the endoscopic findings influenced surgical decisions in 20 of the 33 cases: limiting planned resections in 14, identifying strictures that were previously undetected for repair in one, and deciding against resection in two cases and for extended resection in three [15]. Although intraoperative enteroscopy can influences surgical decisions it is still time consuming and labor intensive. However, if intervention (cautery, dilation, or biopsy) is needed, intraoperative enteroscopy may be an appropriate procedure for some patients. Capsule endoscopy In some patients with small intestinal Crohn’s disease, radiographic studies and push enteroscopy do not provide a diagnosis. Recently capsule endoscopy has been used to examine the entire length of the small intestine. The capsule measures 11  26 mm, and is swallowed by a patient (Figs. 2 and 3). Two images/second are transmitted to a hard drive recorder worn on the patient’s belt.

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Fig. 2. Capsule endoscope. Dimensions: 30 mm  11 mm (photograph courtesy of Given Imaging, Norcross, GA).

Once the exam is completed, the data is downloaded from the recorder into a computer workstation and the video is reviewed. Capsule endoscopy was used in eight patients with symptoms thought to be due to small bowel abnormalities [16]. All patients had undergone previous total colonoscopy and small bowel series within 1 year of entering the study. The patients subsequently underwent enteroscopy with a new wireless video capsule (Given Imaging1, M2A2 Diagnostic Imaging System). Of the eight patients, four had chronic diarrhea and abdominal pain without clear etiology and were suspected of having IBD. The video capsule revealed that two of the four had

Fig. 3. Capsule endoscope internal components: 1. Optical dome, 2. Lens holder, 3. Lens, 4. Illuminating LEDs (Light-Emitting Diodes), 5. CMOS (Complementary Metal Oxide Semiconductor) imager, 6. Battery, 7. ASIC (Application Specific Integrated Circuit) transmitter, 8. Antenna (photograph courtesy of Given Imaging, Norcross, GA).

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ulcerations of the small bowel and one patient showed multiple lesions consisting of erythema, linear ulceration, submucosal edema, and villous-appearing changes in the areas of the mucosa compatible with Crohn’s disease. The fourth patient had a normal study. A second report confirmed the utility of evaluating intestinal lesions in patients suspected with Crohn’s disease [17]. The goal of this study was to evaluate the utility of capsule endoscopy in evaluating colonic lesions. In one patient with chronic diarrhea, apthous ulcers were seen in the colon and led to the diagnosis of Crohn’s disease. This study also illustrated that the capsule endoscope may visualize subtle lesions such as apthous ulcers or arteriovenous malformations that were missed with standard endoscopy. In the future, technological advances in the technology will hopefully allow accurate localization of the findings seen with capsule endoscopy [18]. Accurate localization of lesions may be important in some patients planning surgical resection or helping physicians decide which therapy will be most likely to result in response. Imaging of the entire gastrointestinal tract including the colon may be available in the future, precluding the need for additional diagnostic endoscopy in some instances [19]. However, the need for a tissue diagnosis suggests that standard endoscopy will still play a role in the diagnosis of IBD. This new technology also needs to be compared to current radiographic studies for sensitivity and specificity in detecting lesions in the small bowel. The impact of the information obtained from capsule endoscopy upon the ability to change clinical decisions and impact patient outcomes still needs to be established. For patients with symptoms of bowel obstruction, capsule endoscopy is relatively contraindicated, and if endoscopic visualization of the small intestine is needed, either push enteroscopy or intraoperative enteroscopy are needed. Ileoscopy Ileoscopy through an ileostomy is useful in the evaluation of recurrent disease in patients with small bowel Crohn’s disease. This is best achieved with the patient in the supine position, and often can be done without sedation. Patients with symptoms of disease who have a normal ileoscopy may benefit from capsule endoscopy and/or small bowel radiograph to exclude other evidence of disease. Ileoscopy may also be helpful in determining if patients with ‘‘indeterminate’’ colitis who have undergone a colectomy due to refractory disease truly have Crohn’s disease, prior to a subsequent planned formation of an ileoanal anastomosis. Evidence of Crohn’s disease in the small bowel (or in blind biopsies) would argue against proceeding with the ileoanal procedure, and likely resorting to a completion proctectomy.

Endoscopic therapy Strictures and bleeding are the primary complications of Crohn’s disease for which endoscopic therapy plays a potential role. Although massive bleeding due

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to Crohn’s disease is relatively uncommon, endoscopic therapy can be effective in these patients [20]. Bleeding can occur in any segment of the bowel. Massive hemorrhage is usually the result of an ulcer eroding into a vessel. As with any gastrointestinal bleeding, the patient should be stabilized in the intensive care unit, have blood products available, and have any coagulopathy corrected. In addition to these interventions, patients with bleeding suspected to be due to Crohn’s disease should be treated with high doses of parenteral steroids, to treat the underlying disorder. Cessation of bleeding may be feasible if it is due to diffuse shallow ulceration of the bowel. However, if an ulcer has eroded into a large vessel, surgical or interventional radiographic therapy may be necessary. Crohn’s patients may bleed from any diseased area of the bowel, but acute bleeds are typically from the duodenum (in which case, differentiating a Crohn’s from a peptic source may be difficult), or the ileum. In patients who have already undergone a previous surgical resection, acute bleeds are almost invariably near the site of the previous anastomosis. Luckily, this is typically within the reach of a colonoscope, allowing for attempts at endoscopic therapy. However, in patients without an obvious source should undergo a tagged red blood cell scan and possibly angiography to localize the site of bleeding. Unlike other sources of gastrointestinal (GI) bleeding found by angiography, embolization of the feeding vessels is not recommended due to reports of subsequent perforation due to the induced intestinal ischemia [21]. Should the site be within reach of the enteroscope, push enteroscopy or intraoperative enteroscopy can be attempted. If a discrete source of bleeding is identified, therapy should be performed. There are no data to support either cautery or injection therapy as the treatment of choice, but both have been reported as successful treatment of bleeding ulcers and visible vessels in IBD patients. Surgical intervention is effective in treating persistent bleeding despite endoscopic therapy, or in the case of lesions unamenable to endoscopic attempts. If the patient is stable, and it is obvious that the diseased segment of bowel will need resection, it is probably advisable to proceed straight to surgery, without the delay inherent in a prolonged small bowel endoscopy with attempted therapy. In the case of a Crohn’s patient with multiple affected areas of the small bowel, tattooing of the site of bleeding during a preoperative endoscopy may be helpful in localizing the site for the surgeon, who can then perform a limited resection. Although there have been multiple studies evaluating the use of endoscopic therapy for the dilation of strictures complicating Crohn’s disease, there has been only one case report of balloon dilation of jejunal strictures through an enteroscope [22]. In this report, the patient had multiple jejunal strictures successfully dilated with through the scope balloons. There were no complications, but to date there has been no long-term follow-up on the patient’s clinical course. Currently, through-the-scope balloons are not widely available for enteroscopes, although if the stricture is within reach of a pediatric colonoscope, through-the-scope balloon dilation with standard colonoscope balloons can be attempted. It remains to be seen whether the long-term results are worth the risk of perforation associated with such dilations.

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Summary With the heterogeneous clinical presentation of IBD, endoscopy plays an integral role in the initial diagnosis of Crohn’s disease. Although radiographic tests are often supplemental in the evaluation of Crohn’s disease, they previously had been the only modality available allowing for visualization of much of the small bowel. The advent of small bowel endoscopy allows for direct visualization, and often biopsy, of the small bowel, allowing for confirmation of diagnosing and extent of involvement. Currently, the only mode for obtaining biopsies from beyond the ligament of Treitz is via push enteroscopy or intraoperative enteroscopy. Knowing the extent of disease can also help explain recalcitrant symptoms or lack of response to certain therapies. With the advent of capsule endoscopy, endoscopic visualization of the entire small intestine is now possible with a relatively noninvasive test. Further advancements in capsule endoscopy may relegate push enteroscopy and intraoperative enteroscopy to those cases in which biopsies or therapy are required. In the future, total enteroscopy with new enteroscopes may become more widely available, allowing biopsies and therapy in all segments of the small intestine, without the need for operative intervention.

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