LONDON — Capsule endoscopy received positive reviews in several presentations at the 13th World Congress of Gastroenterology, with speakers championing new applications and technological improvements.
In one of several “state of the art” presentations, Dr. Martin Keuchel of the Asklepios Clinic in Hamburg, Germany, asserted that the minimally invasive technology should already be viewed as a successful first-line screening approach for detection of suspected Crohn's disease associated with obscure gastrointestinal bleeding.
“We have been able to identify nearly 80% of small bowel tumors by capsule endoscopy alone, including those undetectable by other methods. It can be useful for screening for early-stage Crohn's disease, both by stratifying larger tumors needing surgical removal and identifying clusters of smaller polyps and adenomas needing ongoing surveillance,” Dr. Keuchel commented.
Multicenter German trials have shown that the technology detected an overall 2.4% incidence of primary tumors of the small bowel, Dr. Keuchel said. But he acknowledged that one of the main concerns in this setting was the risk of retention, potentially requiring surgical retrieval.
Interestingly, the gastroenterologist observed that this risk was low in early-stage patients who were only suspected of having Crohn's disease. In this situation, when screening was prompted by obscure GI bleeding, the retention rate in the German analysis was only 1.5%, or 10 out of 664 patients.
However, the rate of capsule retention rose to 13% among patients who already had established Crohn's disease.
In an attempt to stave off capsule retention problems, Dr. Keuchel and colleagues tried first using dummy patency capsules in 106 patients with a known stenosis.
These patency capsules have a permeable membrane that allows them to dissolve within 48 hours.
About 50% of the patients were able to quickly excrete the patency capsule, providing evidence that the actual diagnostic capsule was likely to pass as well. But 11 patients reported significant pain from initial retention of the patency capsule; this pain was generally resolved by the capsule's dissolution within 48 hours. One surgical extraction was required, however.
“Small bowel capsule endoscopy has become an accepted first-line diagnostic tool for obscure GI bleeding,” Dr. Keuchel said in summarizing the findings. “It may be the best test for suspected small bowel Crohn's disease, whereas in established Crohn's disease there is a significant risk of retention to be considered, although prior testing with patency capsules appears to reduce this risk significantly.”
“The capsule has clearly revolutionized small bowel imaging, but imaging the colon can be a lot more difficult,” Dr. André Van Gossum of Erasmus Hospital in Brussels said while discussing the next-generation twist for the technology—a so-called “wake-up” capsule that shuts off 3 minutes after ingestion to preserve its battery power for reactivation during its eventual slow pass through the colon.
The capsule is timed to reactivate image broadcasting after 1 hour 45 minutes, when it is predicted to enter the terminal ileum. It can then transmit images during its entire pass through the colon.
Dr. Van Gossum reported on twin pilot studies and a new multicenter trial that appear to show increasing efficacy for the new technology.
He acknowledged that an initial Israeli pilot study of capsule endoscopy in 91 patients, which was first reported in the journal Endoscopy in 2006, had achieved mixed results, with an overall sensitivity of 50%. He ascribed those disappointing results to inadequate preprocedure bowel cleansing.
A second pilot study of 48 patients conducted in Belgium raised sensitivity to 75% by employing a laxative boost to achieve enhanced bowel cleansing and better resultant imaging, the utility of which was further improved by the use of expert readers to interpret the results.
Dr. Van Gossum also noted that his eight-center European trial of 320 patients, first reported in October, had further supported the broad utility of the “wake-up” colon capsule (N. Engl. J. Med. 2009;361:264-70).
The double-headed wake-up camera became activated just as it reached the ileum in 97% of these patients.
And in 93% of the procedures, the capsule was rapidly excreted without retention problems.
The investigator did note that 8% of the patients experienced a variety of adverse events, including nausea, vomiting, and headaches during their preparation.
“In our study, the technology was shown to have a negative predictive value of over 80%, and detected several lesions not seen on colonoscopy. The endoscopy capsule may be considered a complementary tool to colonoscopy or an alternative for patients who resist further probes with colonoscopy—which may occur in 70%. The capsule may soon offer a view of the entire esophageal tract,” Dr. Van Gossum said.