The most recent technologic advance in endoscopy, the capsule endoscope, was approved for clinical use late in 2001. This instrument provides a major breakthrough in the possible diagnosis of diseases involving the small intestinal mucosa.

    The currently available disposable capsule (Given PillCam, Given Imaging) consists of a sealed outer plastic housing that is resistant to breakdown within the gut. The device weights 3.7 g, is 11 mm in diameter, and 26 mm in length. This size allows it to be easily ingested and its capsule shape allows convenient passive passage through the gut. Unlike conventional flexible endoscopes, which require a charged coupled device (CCD) for video imaging, the capsule images are generated by a complementary metal oxide silicon chip camera (CMOS), which has much lower power and illumination needs. Illumination is provided by 4 pulsing white light emitting diodes (LEDs). There are two silver oxide batteries behind the light source followed by an ultrahigh frequency band radio telemetry transmitter completing the inner workings of the device. The image provided has a 140-degree viewing field and a 1:8 magnification of objects from a 1- to 30-mm depth of view. The Given capsule endoscope will transmit two frames per second over a transit time of 7 to 8 hours providing 50,000 to 55,000 color images. Gastric emptying time ranges from less than 1 hour to several hours. Transit through the small intestine ranges from approximately 2 to 5 hours.

    During image transmission, the patient must wear an antenna array over the abdomen. Each of the 8 sensors adhere to the skin in a manner similar to electrocardiogram monitoring electrodes. The antenna system is, in turn, connected to a small portable hard drive worn on a belt along with the power source consisting of 5 “D-cell”-sized nickel-based batteries. The weight from these two system components is supported by suspenders.

    After 8 hours, the recorded images can be downloaded into a customized personal computer-style workstation. The downloading of images is easy to perform and takes 2 to 3 hours. After this, a study is ready for interpretation. Interpretation time ranges from 45 to 90 minutes. The reader has the capability of viewing images over 3 general speeds with the added ability to vary the number of frames viewed per second. When desired, the video stream can be interrupted to view frames individually. Identified abnormalities can be selected, stored, and labeled with a narrative comment individually. The system software offers mapping of the capsule as it courses through the small intestine to help with localization of any findings. The reader must otherwise estimate location of a finding by using the time of entry into the small intestine and exit of the capsule into the colon. Completed studies can be saved onto a CD. In an attempt to increase efficiency and decrease the time required for interpretation, the system is being modified to include pattern recognition software, offering the capability of pre-selecting potential abnormalities for the viewer to evaluate.

    The capsule endoscope is designed to provide an examination of the small intestine. The most common indication for capsule enteroscopy is obscure gastrointestinal bleeding. This is typically performed after routine upper endoscopy, colonoscopy, push enteroscopy, and small intestinal contrast studies have been performed. Attempts are usually made to time the examination as close as possible to any evidence of bleeding, especially in those patients who have obscure recurrent acute or overt bleeding.

    Other potential indications for capsule use that are under evaluation and, in some instances, being applied, are the evaluation of unexplained diarrhea, malabsorptive disorders such as celiac sprue, and inflammatory diseases such as Crohn’s disease.

    Contraindications include known mechanical intestinal obstruction or a history of obstruction, known intestinal strictures (as in Crohn’s disease), Zenker’s diverticulum, intestinal pseudo-obstruction, cardiac pacemakers and defibrillators, and other implanted electomedical devices. Relative contraindications include longstanding history of daily nonsteroidal anti-inflammatory drug (NSAID) use, pregnancy, and large or numerous diverticula.

    It has been necessary in some patients with gastroparesis to endoscopically place the capsule into the duodenum. In patients unable to swallow, the device can be placed through an endoscopically positioned overtube.

    Rarely, the capsule may lodge in the gastointestinal tract. Endoscopic retrieval of the device has been required at the level of the cricopharyngeus and appendical stump. Surgical retrieval for symptomatic obstruction has occurred in patients with unsuspected strictures because of long-standing daily NSAID use and Crohn’s disease. There have been no reports of symptomatic or asymptomatic capsule entrapment within colonic diverticula.

    Because the study requires the patient to wear the antenna and belt pack for 8 hours, most studies are initiated in the morning. Patients are instructed to fast overnight (12 hours). For those patients who will have the procedure initiated late in the day, a minimum of a 4-hour fast is needed. Water may be taken 2 hours after ingestion of the capsule, and meals as well as medications can be taken at 4 hours. Patients are asked to avoid antacids, sucralfate, and iron, all of which may obscure the view. Patients may continue using anticoagulants. They should be encouraged to avoid narcotics and anticholinergics to diminish the risk of reducing gut motility. Patients may pursue their usual activities but are cautioned to avoid physical activity requiring vigorous body movement (e.g., jumping). They may walk, sit, lie down, and drive. The patient maintains a diary and checks on signal transmission by periodically noting a blinking light on the belt pack hard drive. Patients are asked to avoid strong electromagnetic fields such as magnetic resonance imaging and amateur (HAM) radios. They may use a computer, radio, stereo, and cellular phone.

    Approximately 45 minutes are required to enter the data into the workstation (which initializes the recording device to the patient), review the procedure and instructions with patient, prepare the abdomen for the antenna array, and place the belt pack. The capsule is activated by removing it from a magnetic holder.

    Unless the patient has a known swallowing disorder, swallowing the capsule is readily performed with a glass of water. Once the 8 hours have passed, the patient may remove the belt-pack and antenna array and return the system to the endoscopic unit for downloading of the images. Downloading of the data takes 2 to 3 hours. Patients are asked to avoid magnetic resonance imaging for 3 days after the procedure or until the device may be seen to pass in the stool. If there is any question regarding capsule passage, an abdominal radiograph can readily determine whether the device is still in the body. The complete timeline for this procedure is summarized in the following table:

Capsule Endoscopy Procedure Timeline
Duration (h)

Patient Overnight fast 12
Staff Patient initialization into system software 0.75

Patient instruction
Recording system set-up and patient fitting

Patient Image acquisition 8
Staff Image downloading 2-3
Physician Study interpretation 1-1.5

    Capsule endoscopy has enhanced our ability to evaluate the small intestinal mucosa of adults. Currently, the primary use of capsule endoscopy is in the evaluation of the patient with obscure gastrointestinal bleeding. The indications are limited to diagnostic imaging because there is currently no ability to sample tissue or perform therapy with the capsule. Future capsule designs may emerge with expanded capabilities that include fluid sampling, mucosal biopsy, targeted labeling, and controlled movement. With future innovation and study, the indications for capsule endoscopy will likely expand and become more focused.

For more information go to: www.givenimaging.com