How to Prevent Endoscopic Capsule Retention

Capsule endoscopy allows visual examination of the entire length of the intestinal mucosa in a noninvasive manner. Since its marketing release in 2001, it has become the gold standard in evaluating suspected disease of the small bowel [1] [2]. Having a capsule caught, trapped, or retained in the small bowel remains a major concern for physicians performing capsule endoscopy, since it could possibly lead to a need for surgery in a patient who would otherwise have been treated medically for the same illness. This has been thought to be apply in particular to patients with Crohn’s disease or nonsteroidal anti-inflammatory drug (NSAID) enteropathy. In addition, it has been postulated that retention could cause acute small-bowel obstruction if the capsule became impacted in a stricture. Other causes of retention reported in the literature have included small-bowel tumors, radiation enteritis, and surgical anastomotic strictures. There is no clear medical therapy for these conditions, and surgical management of them has therefore limited concerns regarding capsule retention. Capsule retention has not been reported in so-called normal anatomy or anatomical variants such as colon or small-bowel diverticulosis and appendiceal orifices. Experience has shown that the risk of capsule retention is related to the indication for the examination. The rate of retention in patients with obscure gastrointestinal bleeding is 1.5 %, based on the reported 15 cases out of 1089 [3] [4] [5]. In patients with known Crohn’s disease, the rate of retention is 5 %, based on four cases out of 80 [6] [7]. In patients with suspected Crohn’s disease, the retention rate is 1.4 %, based on one case out of 71 [8] [9] [10] [11]. When capsule endoscopy was carried out in young healthy volunteers during a pharmaceutical trial, no cases of capsule retention were reported in 773 ingestions [12].

Many investigators have been interested in finding ways of avoiding retention in patients who are thought to be at risk and who are to undergo capsule endoscopy. A normal small-bowel series does not exclude the presence of small-bowel strictures and thus does not protect the patient from having capsule retention. When the data from published studies are combined, a total of 20 cases of capsule retention have been reported, in which 17 of the patients had normal small-bowel series before their examinations. The other three did not undergo small-bowel radiography before their capsule examinations. Computed-tomographic (CT) enteroclysis has been advocated as a means of avoiding capsule retention. Voderholzer et al. [14] reported examining 56 patients with Crohn’s disease. Strictures were identified in 15 of the patients (27 %), who therefore did not undergo capsule examinations, while the remaining 41 patients underwent successful capsule endoscopy after CT enteroclysis.

The patency capsule (Given Imaging, Ltd., Yoqneam, Israel) was also developed in an attempt to avoid retention [14] [15] [16]. This self-dissolving capsule is the same size as a capsule endoscope. The cellophane-walled cylinder is filled with lactose with 10 % barium to create radiopacity, and it is protected by a wax plug at one end with a specifically sized hole that allows the influx of intestinal fluid, which in turn dissolves the lactose in 120 h or 5 days. In addition, the patency capsule contains a transponder device that allows it to be detected by a hand-held scanner placed close to the anterior abdominal wall. The intention in developing the patency capsule was that patients with suspected strictures would be to swallow the capsule without risk. In initial premarketing studies, the capsule passed from the body in 72 h or 3 days in 95 % of healthy individuals. The abdomen can be scanned after 96 h or 4 days to determine whether the capsule has passed. Of course, the capsule may still be in the colon at that time, and the scanning findings may be false-positive. This device was approved for use in Europe in 2004, but has not yet been cleared by the Food and Drug Administration in the United States.

This issue of Endoscopy includes three different reports on the patency capsule. Delvaux et al. report that the patency capsule decreases in size as the lactose dissolves and that it can then become impacted in a stricture and cause obstruction of varying degrees of severity [15]. Patients may have temporary pain, or acute obstruction requiring surgery. For use in the United States, the patency capsule has been redesigned with wax plugs with holes at both ends to ensure that intestinal juice can enter the capsule to speed up its dissolution and prevent the slow decrease in capsule size that can lead to impaction within a stricture. Studies of this new patency device are underway.

The ideal method of identifying intestinal strictures before capsule endoscopy in an effort to avoid retention is not yet clear. There is no accepted method that will completely prevent capsule retention, but it is clear that obtaining a good medical history is the best single method. A potential for capsule retention should be suspected in patients with abdominal pain, distension, and nausea. Other risk factors include known Crohn’s disease and a history of chronic NSAID use. A history including small-bowel obstruction, previous small-bowel resection, or previous abdominal surgery are not indicators of probable retention. A normal small-bowel series does not preclude retention. Data are still lacking concerning the use of other preexamination studies to prevent retention. CT enteroclysis is promising, as mentioned above. Unfortunately, this requires nasal and then duodenal intubation, along with multidetector CT scanning. Its relatively invasive nature in comparison with capsule endoscopy will probably preclude its use in large numbers of patients. It has been suggested that multidetector CT enterography could be of use in identifying areas of narrowing, but there are no data at present to support this opinion. It is clear from the papers published in this issue of Endoscopy that the ideal design for and use of the patency capsule are still being developed.

At this year’s annual International Conference on Capsule Endoscopy (ICCE), a working group developed a consensus statement concerning capsule retention [17]. They defined capsule retention as a capsule endoscope remaining in the digestive tract for a minimum of 2 weeks. Capsule retention was defined also as the capsule permanently remaining in the bowel lumen unless extracted by endoscopic or surgical methods, or if passed as a result of medical therapy. If capsule retention is suspected or if the colon is not entered during the acquisition time, the consensus statement suggests that an abdominal radiograph should be obtained after 2 weeks. Radiography should be considered in particular if there are symptoms of obstruction and if the patient needs to undergo magnetic resonance imaging, has one of the risk factors of NSAID use or known Crohn’s disease, or needs reassurance that the capsule has passed.

Once retention has been diagnosed, only endoscopic and surgical intervention have been shown to be effective in removing the capsule. There are no data regarding the success of medial therapies for retention, such as initiating a course of steroids or infliximab, stopping NSAIDs, or using prokinetics or cathartics to assist with passage of the capsule. To date, reports indicate that long-term capsule retention is not associated with any sequelae. The longest period of retention reported to date is 2.5 years [5]. There is therefore no time limit for instituting management to remove the capsule. However, to quote the consensus statement, ”surgical intervention not only allows removal of the capsule endoscope but also, perhaps more importantly, can remove the offending pathology that caused capsule retention and the reason for the capsule examination in the first place.“

References

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