After an 8- to 12-hour fast, the patient swallows the video capsule, which peristalsis then carries through the gastrointestinal (GI) tract. The minuscule (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/s and are transmitted via UHF band radio telemetry to a data recorder worn around the patient's waist.

Approximately 60,000 high-quality color images are recorded during each video capsule endoscopy (VCE) procedure. These images are compiled into a digital video (see the video below), which is then read at a workstation. Currently available 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, it is less accurate for lesions that are not actively bleeding at the time of evaluation. [55, 62]

Video of capsule endoscopy from patient with gastrointestinal bleeding. View Media Gallery

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]