Inflammatory bowel disease (IBD) is a generic term used to describe Crohn disease (CD), ulcerative colitis (UC) or IBD type unclassified (IBDU), formerly known as indeterminate colitis. By definition, only CD has the possibility to involve the whole gastrointestinal tract. However, in 10% to 15% of cases, a change in diagnosis is made from UC to CD or vice versa.
There is no absolute diagnostic test for IBD. The correct classification for CD and UC relies in the use of a combination of endoscopic, histologic, radiologic, and biochemical investigations.
The terminal ileum is the most common area affected by CD and it is usually accessible at the time of colonoscopy. In approximately one third of patients with ileocolonic CD, the proximal small-bowel (SB) may be the only area of the gastrointestinal tract affected. Therefore, it is important to maintain a high degree of suspicion in the appropriate clinical setting, even with a normal colonoscopy with terminal ileal intubation.
In the past, the endoscopic visualization of the small intestine was limited to the terminal ileum during colonoscopy and to the proximal jejunum during push enteroscopy. The majority of the SB was not seen endoscopically and was evaluated with radiologic tests such as small bowel follow-through (SBFT) or enteroclysis.
Our current armamentarium for the investigation of the gastrointestinal tract involves cross-sectional radiologic imaging tests, such as computed tomographic enterography (CTE) and magnetic resonance enterography (MRE; see the article on the radiologic evaluation of IBD), deep enteroscopy with balloon-assisted or overtube-assisted endoscopy, collectively called device-assisted enteroscopy, and wireless video capsule (capsule endoscopy). Each technology has its own strengths and weaknesses. They should be viewed as complementary studies and not mutually exclusive.
This article focuses on the role of capsule endoscopy in IBD in adults. We discuss the use of capsule endoscopy in suspected CD, established CD, UC (including ileal–anal pouch anastomosis), and IBDU.
Preparation
Capsule endoscopy, as opposed to regular endoscopy, does not have the ability to clean the mucosa or eliminate bubbles, debris, or bile during the procedure. Thus, bowel preparation should be used. There is no consensus about patient preparation for capsule endoscopy. In the setting of IBD, especially in established CD patients, SB strictures should be considered before proceeding with capsule endoscopy. Some clinicians perform SBFT, CTE, or MRE before capsule endoscopy. A patency capsule (a capsule that dissolves in case of impaction) can also be used to investigate for significant stenosis. Others advise to use the patency evaluation only in those individuals where an obstruction is suspected or highly probable.
Each practice seems to use a different combination of dietary fasting, laxatives, and medications to stimulate peristalsis. Our group uses a full bowel preparation in a split dose regimen, followed by 10 mg of metoclopramide and 80 mg of simethicone orally 30 minutes before capsule ingestion. This regimen had good to excellent cleansing in 94% of patients versus 76% ( P <.001) with fasting alone in the proximal SB and 55% versus 37% ( P = .01) in the distal SB. A meta-analysis evaluating purgative preparation versus clear liquids diet found similar results where purgative preparations had a higher diagnostic yield (odds ration [OR], 1.813; 95% confidence interval [CI], 1.251–2.628; P = .002), and SB visualization quality (OR, 2.113; 95% CI, 1.252–3.566; P = .005).
There is no standardized method to report SB cleansing in capsule endoscopy. The examination is enhanced when clear of debris, air bubbles, and bile. A popular technique for formal evaluation of cleansing during clinical investigation is to observe the images every 5 minutes (2-minute duration) and report the quality of the preparation analogously to the colon cleansing score on colonoscopy. For research purposes and patient quality measures, an ideal score should be easy to use, quick, and with excellent reproducibility.
A recent score has been suggested using the proportion of the visualized mucosal and the degree of bubbles, debris, and bile obscuring the mucosa in 1 frame every 5 minutes. The investigators compared it with the standard 2 minutes of assessment every 5 minutes. The concordance with the standard method, the interobserver agreement and intrapatient agreement were excellent (κ = 0.82, κ = 0.8, and κ = 0.76, respectively).
After ingestion of the capsule device, the patient should monitor its passage. If the patient does not notice the passage of the capsule after 14 days or has symptoms of partial or complete SB obstruction, radiologic examination is recommended. Unpassed capsules can be retrieved endoscopically or surgically.
Capsule Endoscopy Findings are Nonspecific
IBD is diagnosed by clinical, pathologic, radiologic and endoscopic means. There is no single test to diagnose CD or UC. Physicians rely on all the information obtained to being able to correctly diagnose a patient. Endoscopy allows for mucosal evaluation, and also permits tissue acquisition and performance of therapeutics, such as stricture dilation. Capsule endoscopy is able to provide image acquisition, but it cannot obtain biopsies or perform therapeutics.
The SB has limited ways to demonstrate injury: Mucosal disruption (erosions and ulcers), erythema, villous blunting, and strictures. These findings are easily captured by capsule endoscopy, but are not pathognomonic of IBD. Any type of injury can produce similar findings such as nonsteroidal anti-inflammatory drugs (NSAIDs), ischemia, and celiac disease, and these findings may be present in normal individuals. Even as little as 2 weeks of standard dose NSAID use can cause SB injury in 75% of asymptomatic individuals. Moreover, 20% of normal individuals may have mild mucosal abnormalities.
One can then appreciate that capsule endoscopy findings are very nonspecific and should not be used solely to diagnose IBD. It is very important to exclude the use of NSAIDs, even in usually prescribed or over-the-counter doses.
Specific Situations
Suspected and Established CD
In the majority of patients with suspected CD, the diagnosis can be confirmed by colonoscopy with ileal intubation. In approximately 30%, the proximal SB may be the only affected area.
A study examining the performance characteristics of different combinations of colonoscopy (with ileal intubation), CTE, capsule endoscopy, and SBFT found that colonoscopy with either CTE or SBFT was more accurate than capsule endoscopy with CTE, SBFT, or colonoscopy, secondary to the low specificity of capsule endoscopy. This suggests that capsule endoscopy may be reserved for patients with strong clinical suspicion for CD with unremarkable colonoscopy and radiologic evaluations. Conversely, capsule endoscopy has a high negative predictive value (96%–100%). In other words, an unremarkable capsule endoscopy evaluation virtually excludes SB CD.
The findings on capsule endoscopy in CD are nonspecific and should be interpreted with caution. Studies define the primary endpoint as the “diagnostic yield” (number of examinations with abnormal findings divided by the number of total examinations), which should not be confused with sensitivity (the number of true-positive examinations divided by the number of true-positive and false-negative examinations), or specificity (the number of true-negative examinations divided by the number of true-negative and false-positive tests). A test with high diagnostic yield does not mean that it is a sensitive or specific test. Moreover, there is no standard definition of what constitutes CD on capsule endoscopy. The most common accepted definition for SB involvement in CD is the presence of 3 or more ulcerations. This definition had a 50% positive predictive value for a diagnosis of CD. The significance of minor mucosal changes is uncertain and caution should be applied not to overdiagnose CD and expose the patient to unnecessary risk from escalation of therapy.
There are 2 scoring systems to quantify the extent of small intestinal disease in CD. The Lewis Index uses 3 parameters: villous edema, ulceration, and stenosis (weight based on severity and extent). The other system is called Capsule Endoscopy Crohn Disease Activity Index (CECDAI). It divides the SB into proximal and distal segments and uses different weights for 3 parameters: Inflammation, extent of disease, and stricture. The final score is the sum of the proximal and distal segmental numbers. It ranges from 0 (normal study) to 36 (severe disease). The agreement for the CECDAI score was excellent at 0.867. External validation of these scores is awaited but the CECDAI appears easy to use and has a high degree of interobserver agreement.
It seems that capsule endoscopy is a better study to exclude SB involvement in CD rather than confirming it.
Capsule Endoscopy and Plain Abdominal Radiology
SBFT x-ray and enteroclysis remain available, but there has been a trend toward using more accurate diagnostic tests, such as CTE and MRE. Overall, capsule endoscopy has a higher mucosal diagnostic yield for patients with suspected or established CD compared with SBFT and enteroclysis, ranging from 49% to 93% versus 12% to 67%, respectively. These studies have excluded patients with suspected or known SB strictures.
Meta-analyses evaluating the performance of CE versus SBFT/enteroclysis showed better performance of capsule endoscopy with an incremental yield (IY) of 32% favoring capsule endoscopy ( P <.0001; 95% CI, 16%–48%).
Capsule Endoscopy and MRE
Earlier studies with small numbers of patients with suspected and established CD suggested that capsule endoscopy and MRE had similar performance characteristics with good correlation between the 2 techniques. Capsule endoscopy detected slightly more mucosal disease and MRE identified more extraintestinal manifestations, such as strictures, fistulae, and abscesses. A meta-analysis did not show a difference between the 2 studies.
A prospective trial of 93 patients compared the diagnostic accuracy of capsule endoscopy, MRE, and CTE for terminal ileal disease in patients with suspected or established CD using ileocolonoscopy with biopsy as the gold standard. Sensitivity for capsule endoscopy, MRE, and CTE was 100% (95% CI, 79%–100%), 81% (95% CI, 58%–95%), and 76% (95% CI, 53%–92%), respectively; specificity of 91% (95% CI, 79%–97%), 86% (95% CI, 74%–94%), 85% (95% CI, 72%–93%), respectively. There was statistical difference in sensitivity compared with CTE, but only a trend compared with MRE and no statistical difference was seen in the specificity.
Capsule Endoscopy and Computed Tomography Enterography
Computed tomography enterography is the most commonly used technique to investigate SB involvement in CD given its ease to use, reliability, and lower cost compared with MRE. It has the disadvantage of ionizing radiation exposure. Studies comparing CTE and capsule endoscopy showed a higher diagnostic yield of capsule endoscopy but no significant difference was seen. However, the prospective study mentioned did show a higher sensitivity of capsule endoscopy versus CTE for terminal ileal involvement with CD (100% vs. 76%; P = .3), but no difference was found for specificity.
A meta-analysis found that capsule endoscopy had a higher diagnostic yield than CTE in both suspected and established CD patients (IY, 47%; 95% CI, 31%–63% [ P <.00001] and IY, 32%; 95% CI, 16%–47% [ P <.0001]).
Capsule Endoscopy and Other Endoscopic Techniques
There are several other endoscopic techniques to evaluate the SB mucosa: Push enteroscopy, intraoperative enteroscopy, balloon-assisted deep enteroscopy, and device-assisted deep enteroscopy. Capsule endoscopy is less invasive compared with the other techniques, but does not allow for tissue acquisition or for therapeutics to be performed.
The results of CE seem to be comparable to both push enteroscopy and balloon-assisted enteroscopy in the assessment of SB disease. In the cases where an intervention is planned, such as stricture dilation or retrieval of a foreign body, capsule endoscopy findings are useful to suggest which route to take: Antegrade or retrograde. Specifically for patients with suspected or established CD, capsule endoscopy has a higher diagnostic yield than push enteroscopy with enteroclysis and, in this study, led to a change of management in 70% of patients.
IBDU
Formerly known as “indeterminate colitis,” the term IBDU represents a colonic IBD, without SB involvement, for which a definite diagnosis of either CD or UC could not be made after ileocolonoscopy, biopsies, and SB radiology. Indeterminate colitis is reserved for colectomy specimens where a diagnosis of CD or UC cannot be made. It is unclear at this time the role of capsule endoscopy in patients with IBDU. Studies have shown that, in patients with IBDU, the SB may show changes suggestive of CD in 16% to 39% of patients, but it resulted in no change in management in the majority of patients. In patients with UC and IBDU undergoing colectomy, preoperative capsule endoscopy findings do not predict ileal–anal pouch outcomes, such as pouchitis or pouch dysfunction.
UC
A diagnosis of UC does not involve the SB; thus, capsule endoscopy is generally not recommended. Some experts suggest that a SB evaluation should be considered, particularly in patients with severe refractory UC before colectomy. This is supported by 1 study of patients with equivocal diagnosis of UC, including a patient with ileal–anal anastomosis, which showed that 61% had changes suggestive of CD.
Potential Indications
The role of capsule endoscopy in the management of IBD is still unclear. Some potential indications for capsule endoscopy are shown in Box 1 .
Related posts:
Health Maintenance in the Inflammatory Bowel Disease Patient
Detecting and Treating Clostridium Difficile Infections in Patients with Inflammatory Bowel Disease
The Promise and Pitfalls of Serologic Testing in Inflammatory Bowel Disease
Evaluation for Postoperative Recurrence of Crohn Disease
Patient-Specific Approach to Combination Versus Monotherapy with the Use of Antitumor Necrosis Factor α Agents for Inflammatory Bowel Disease
Imaging for Luminal Disease and Complications: CT Enterography, MR Enterography, Small-Bowel Follow-Through, and Ultrasound
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
