Capsule Endoscopy Technique

Updated: Dec 04, 2015
  • Author: Ruben Peralta, MD, FACS; Chief Editor: John Geibel, MD, DSc, MSc, AGAF  more...
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Technique

Video Capsule Endoscopy

After an 8- to 12-hour fast, the patient swallows the video capsule, which peristalsis then carries through the gastrointestinal (GI) tract. The miniscule (11 × 30 mm) capsule contains a miniature complementary metal oxide silicon chip video camera, white light–emitting diode illumination sources, a power source, and a UHF band radio telemetry transmitter (see the image below). Digital images of the GI tract mucosa are recorded at a rate of 2 frames/sec and are transmitted via UHF band radio telemetry to a data recorder worn around the patient's waist.

Equipment for capsule endoscopy. Equipment for capsule endoscopy.

Approximately 60,000 high-quality color images are recorded during each procedure. These images are compiled into a digital video (see the video below), which is then read at a workstation. Newer software detects video frames likely to contain blood and marks these for closer examination. [7] For actively bleeding lesions, this software is highly accurate; however, its accuracy falls significantly for lesions that are not actively bleeding at the time of evaluation. [48, 55]

Video of capsule endoscopy from patient with gastrointestinal bleeding.

The camera lens has a short focal length that enables it to capture images as it passes the mucosa. At a magnification of 1:8, the capsule is able to detect lesions as small as 0.1 mm within a field of view as wide as 140º. [6] The position of the capsule within the abdomen may be estimated to within 3 cm and is calculated on the basis of the strength of the signal detected by external sensors. [7]

The patient may remain ambulatory for the procedure. In initial studies, the mean mouth-to-evacuation transit time was 24 hours. [8]

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Complications

Few complications are associated with capsule endoscopy. The most serious adverse event, capsule retention, is relatively uncommon (1-3%) but can have significant sequelae, including the need for emergency surgery. [56, 57] Capsule retention rarely produces symptoms. [5, 7]

In a review of 937 capsule endoscopies, no major complications were reported, and fewer than 1% of patients required surgical removal of the device. [58] For capsules that may have been retained, an abdominal radiograph should be obtained. Several risk factors for capsule retention have been identified, including dysphagia, gastroparesis, previous abdominal irradiation, prolonged use of nonsteroidal anti-inflammatory drugs (NSAIDs), and small-bowel strictures from Crohn disease. [58, 6]

To test for GI tract patency, a dissolvable capsule has been developed that can be administered before VCE. If the capsule is passed intact, no obstruction should be present; if the capsule is retained, it dissolves within 40 hours. [59, 6] A study by Nemeth et al suggested that nonselective use of the patency capsule in patients with established Crohn disease may not significantly reduce video capsule retention. [60]

A barium series before capsule endoscopy may detect some strictures, though it may not be as sensitive for the detection of partial obstruction. Capsule retention is possible despite typical radiographic results on barium studies. [7, 6]

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