Video Capsule Endoscopy: Recent Advances in Diagnosis

Investigation of the small intestine or the esophagus with conventional diagnostic and imaging modalities can be challenging. Video capsule endoscopy is a relatively new and noninvasive technique that allows direct visualization of the small bowel or the esophagus and can obviate the need for or guide the use of more invasive procedures. The capsule contains a miniature camera that takes pictures of the lining of the small intestine or the esophagus. Unlike conventional diagnostic procedures, video capsule endoscopy can often successfully identify the source of the problem quickly and painlessly. It is also useful in assessing patients with a variety of other conditions affecting the small intestine or the esophagus, including Crohn's disease, celiac disease, tumors, reflux disease, esophagitis, and Barrett's esophagus.

Resident, Internal Medicine; Muhammad Hasan, MD, Chief Resident, Internal Medicine; Salman Khan, MD, Resident, Internal Medicine; Verapan Vongthavaravat, MD, Assistant Professor, Section of Digestive Disease, University of Oklahoma Health Sciences Center, Oklahoma City, Okla

Tauseef Ali, MD,

An estimated 19 million people in the United States suffer from diseases of the small intestine, such as obscure bleeding, Crohn's disease, chronic diarrhea, or cancer.¹ The invention of fiberoptic endoscopy made visualization of the entire stomach, upper small bowel, and colon possible. However, conventional visualization and imaging techniques for diagnosing small bowel disorders are unsatisfactory. For example, push enteroscopy can evaluate only about 80 to 120 cm distal to the ligament of Treitz, while barium follow-through and enteroclysis offer indirect examination of the small bowel, with a low diagnostic yield, particularly when the offending lesion is flat (eg, vascular malformation).² The need for endoscopic examination of the small bowel is now well established, not only for evaluating obscure gastrointestinal (GI) bleeding but also for the diagnosis and screening of small bowel tumors, polyposis syndromes, and inflammatory diseases. Endoscopic examination is also used to diagnose common upper GI diseases, such as gastroesophageal reflux disease or Barrett's esophagus.

In 1981, the Israeli physician Gavriel Iddan, MD, came up with the idea of a video camera that would fit inside a pill. It took 20 years for technology to catch up with Dr Iddan's vision and, after several larger wireless endoscopy prototypes, the wireless video capsule endoscopy (VCE) was developed. The VCE technique is marketed as PillCam SB (previously known as M2A) for GI diagnosis and, more recently, also as PillCam ESO for visualization of the esophagus. In August 2001, the Food and Drug Administration (FDA) approved the PillCam SB for clinical use of the small bowel after several successful clinical trials investigating its use for the diagnosis of obscure GI bleeding.¹ In November 2004, the FDA approved the PillCam ESO for the diagnosis of reflux-associated conditions.

The small bowel is anatomically challenging to diagnose. Endoscopic techniques for detecting small intestine abnormalities include push enteroscopy, sonde enteroscopy, intraoperative endoscopy, and now VCE. Acomparison of these modalities is presented in the Table.

Approximate diagnostic yield of the small intestine is 5% with radiology, 35% with enteroscopy, and 60% with VCE.¹ Because of the advantages of VCE, especially in terms of diagnostic yield, it might eventually replace traditional invasive and time-consuming diagnostic enteroscopy and become the first choice for examining patients with obscure GI bleeding and other small bowel diseases. Once a diagnosis is made with VCE, subsequent management can be determined. If a lesion is found in the upper part of the small intestine, for example, push enteroscopy may be used to obtain biopsy specimens and perform endoscopic interventions.

The VCE Components

The Given diagnostic imaging system includes 3 main components: the video capsule, a data recorder, and a workstation for reporting and processing images and data. The capsule contains a minuscule color video camera with a flash, watch battery, transmitter, and antenna, all of which are embedded within a regular-sized capsule that has to be swallowed, which can usually be done easily. Images are obtained at a rate of 2 per second. It transmits a signal that relays information to the recorder about its location, allowing the system to track the capsule as it passes through the esophagus or the GI tract.

A recorder receives the data transmitted by the capsule. This portable Walkman-sized, battery-operated unit attaches to a belt and is worn by the patient during the procedure. It includes a receiver, processor module, and hard disk drive for sorting the data. The data recorder is ready for operation once the battery pack and sensor array are connected. Ablue, blinking, light-emitting diode indicates when the data are recorded. Eight identical, 4-cm in diameter, flexible, printed circuit board sensors (which are attached to the skin with disposable adhesive pads) receive data from the capsule by means of radiotelemetry. The data recorder acquires up to 50,000 images during approximately 7 hours.

The Reporting and Processing of Images and Data (RAPID) workstation is a modified standard personal computer designed for the storage, presentation, and processing of the acquired images. It also generates reports. ARAPID application software program is installed on the hard drive of the workstation. The images captured by the camera are seen as a "movie" comprising from 1 to 50 frames per second depending on the selected movie speed; usually 5 or 10 frames per second are used. The movie can be paused and reversed.

Indications for Video Capsule Endoscopy

Use of VCE is now approved for the diagnosis of several GI conditions as well as for imaging of problems associated with the esophagus, when no contraindications exist. Indications include:

1. Detection of the source of obscure (microscopic) GI bleeding after conventional work-up (ie, small bowel endoscopy, colonoscopy, small bowel series) has been completed or has not revealed a source. Two recent studies found that VCE yielded a diagnosis in 51% to 63% of patients with obscure GI bleeding.^3,4 In a third, smaller study, VCE was superior to push enteroscopy in identifying the source of obscure GI bleeding (ie, 74% of patients vs 19%, respectively).⁵ In almost one fourth of these patients, VCE findings led to a successful change in treatment strategy.⁵

2. Assessment of the extent of Crohn's disease in the small bowel. It may also have a role in the diagnosis of patients with suspected Crohn's disease.^6-8 In one study of 35 patients, VCE was successful in diagnosing 77% of patients with suspected Crohn's disease, compared with 23% for barium small bowel follow-through and 20% for computerized tomography.⁸ The authors of a recent article on this topic, published last year, concluded that VCE "can be recommended as part of the routine work-up in patients with obscure bleeding or iron-deficiency anemia. In patients with Crohn's disease, the method may be helpful in establishing or ruling out the diagnosis."⁹

3. Evaluation of chronic diarrhea, as well as detecting small bowel tumors, assisting in the surveillance of small bowel polyps and premalignant disorders, including Gardner's syndrome, detecting small bowel injury associated with the use of nonsteroidal antiinflammatory drugs, and delineating whether abdominal pain is functional or organic. It is important to note that the current design of the capsule does not allow easy visualization of colonic lesions, although occasionally, abnormalities may be demonstrated with this technique in the cecum.

4. Diagnosis of the esophageal mucosa, especially in relation to conditions associated with reflux problems or Barrett's esophagus. Note that it should not be used when the patient has swallowing difficulties, since the capsule has to be swallowed.

Some GI findings that can be expected with VCE are shown in Figures 1-4 and esophageal findings in Figure 5.

Contraindications

The main contraindications for VCE include patients with known or suspected GI obstruction, strictures, or fistulae. Other contraindications include Zenker diverticulum, swallowing disorders, pregnancy, gastroparesis, multiple previous abdominal surgeries, or situations in which the patient cannot (or refuses to) undergo surgery.

This type of endoscopy is relatively contraindicated in patients with implanted pacemakers or defibrillators. The initial concern was that the signals from the capsule might interfere with the pacemaker or defibrillator. However, VCE has been safely used in patients who have these devices.¹⁰

Patient Preparation

Before the procedure, the patient must empty the stomach and small intestine so that retained food particles and fluid do not obstruct the mucosa and hide lesions. Because of the small size and flatness of the involved lesions in GI imaging (ie, angiodysplasias, linear ulcerations), they could easily be concealed under a small amount of fluid.

Strict fasting, including abstaining from all liquids, is adequate to clear the small intestine in most people, but some may require a promotility agent or a lengthened fasting period. Recent evidence indicates that bowel preparation (eg, oral sodium phosphate or a polyethylene glycol/electrolyte solution) can improve visualization of the small intestine compared with overnight fasting alone.^11,12

The manufacturer's guidelines (available at www.givenimaging.com) indicate that the patient can have up to 2 meals by noon on the day before the procedure, followed by a clear liquid diet. During the 10 hours before the procedure, fasting is recommended. Some dietary products, medications, and smoking may stain the small bowel's mucosa and affect the capsule's visibility by dimming the lighting and resulting in images that may be too dark for adequate assessment. Therefore, some of these agents (eg, iron, sucralfate) are restricted beforehand and all should be restricted during the procedure.

Cell phones, computers, pagers, and home stereo equipment do not interfere with the capsule's functioning and can be used during the procedure, but radio equipment (eg, a Ham radio or close proximity to a radio broadcasting tower) can interrupt the capsule's signal and cause data loss.¹⁰

The patient should sign either a consent form or a form that discloses associated risks and intra-and postprocedure instructions. Patients should also be instructed on how to use the patient diary and be told about activity restrictions and the need for frequent checks of the data recorder. They should be given a phone number for contacting the endoscopy staff and be informed about symptoms that must be reported immediately and that they must return to the facility after 8 hours.

The Procedure

After verifying that the patient has fasted overnight, the belt/suspender device that holds the data recorder is fitted to the patient. A computer program will have been used earlier to link the patient to a data recorder for the study. Before swallowing the capsule, the sensor array leads are placed securely on the specified sites of the abdomen. To ensure that the leads will stay in place, the abdomen may need to be shaved.

The 11 x 26 mm video capsule is swallowed with water. Clear fluids can be taken 2 hours later. Four hours after the study's start time, the patient can have a small snack. Six hours after the study's start time, the patient can have the first meal and resume taking medications that were restricted before the study. The belt is removed after 8 hours and the recorded images are downloaded to a workstation. The image management software then creates a video. Viewing of the video, selection of images, and generation of a report can take 30 to 90 minutes.

VCE can be performed as an outpatient procedure. However, patients should return to the clinic or office after 8 hours for removal of the recorder and belt.

Risks, Potential Complications, and Costs

The main risks involved in VCE are perforations and entrapment of the capsule; these can require surgical or invasive endoscopic intervention.

Potential complications involve capsule retention and failure to properly image the designated area. In the largest series reported to date, involving 900 patients evaluated primarily for obscure GI bleeding, capsule retention occurred in 0.7% of cases.¹³ Failure to uniformly image the entire small bowel is a potential shortcoming. With the current battery life of approximately 8 hours, the entire small bowel may not be visualized in a significant number of patients. A multicenter retrospective evaluation of 195 procedures found that the entire small bowel was adequately visualized 78% of the time.⁹

The chief barriers to greater widespread use of VCE appear to be cost and the physician time necessary to interpret the images.¹⁴ The initial cost of the hardware and software is approximately $32,000. Each nonreusable video capsule costs $450. Unpredictable and variable reimbursements from Medicare and private insurance carriers have led some physicians to conclude that the level of compensation for their interpretive time may be unsatisfactory, despite the potential importance of the information that can be obtained.¹⁴

Conclusion

Video endoscopy is an exciting new diagnostic technique for assessing the lumen of the digestive tract or now even the esophagus. However, at the moment, it is mainly used as an adjunct to upper and lower GI endoscopy. Atherapeutic VCE may one day be developed. In January 2004, VCE received a current procedural terminology code, which can alleviate one obstacle to its widespread use.¹⁵

SELF-ASSESSMENT TEST

1. All these techniques can view the entire small intestine, except:

• Sonde enteroscopy
• VCE

2. VCE has all these features, except:

• It is an outpatient procedure
• It can obtain biopsy specimens

3. VCE is indicated for all of the following, except:

• Assessing the extent of Crohn's disease
• Evaluating chronic diarrhea

4. Which technique requires the most physician time?

• Sonde enteroscopy
• VCE

5. All the following conditions are contraindications to VCE, except:

• Fistulae
• Strictures

(Answers at end of reference list)

Gastroenterol Nurs

1. Yu M. M2A capsule endoscopy. A breakthrough diagnostic tool for small intestine imaging. . 2002;25:24-27.

Med J Aust.

2. Chong AKH, Taylor ACF, Miller AM, et al. Initial experience with capsule endoscopy at a major referral hospital. 2003;178:537-540.

Can J Gastroenterol.

3. Enns R, Go K, Chang H, et al. Capsule endoscopy: a single-centre experience with the first 226 capsules. 2004;18:555-558.

Can J Gastroenterol

4. Tang SJ, Christodoulou D, Zanati S, et al. Wireless capsule endoscopy for obscure gastrointestinal bleeding: a single-centre, oneyear experience. . 2004;18:559-565.

Ailment Pharmacol Ther

5. Mata A, Bordas JM, Feu F, et al. Wireless capsule endoscopy in patients with obscure gastrointestinal bleeding: a comparative study with push enteroscopy. . 2004;20:189-194.

Endoscopy.

6. Herrerias JM, Caunedo A, Rodriguez-Tellez M, et al. Capsule endoscopy in patients with suspected Crohn's disease and negative endoscopy. 2003;35:564-568.

Gut

7. Fireman Z, Mahajna E, Broide E, et al. Diagnosing small bowel Crohn's disease with wireless capsule endoscopy. . 2003;52:390-392.

Dig Liver Dis.

8. Eliakim R, Suissa A, Yassin K, et al. Wireless capsule video endoscopy compared to barium follow-through and computerized tomography in patients with suspected Crohn's disease?final report. 2004;36:519-522.

Endoscopy

9. Maieron A, Hubner D, Blaha B, et al. Multicenter retrospective evaluation of capsule endoscopy in clinical routine. . 2004;36:864-868.

Gastroenterology.

10. Lewis BS. Complications and contraindications in capsule endoscopy [abstract]. 2002;122;M1656.

Scand J Gastroenterol.

11. Niv Y, Niv G. Capsule endoscopy: role of bowel preparation in successful visualization. 2004;39:1005-1009.

Gastrointest Endosc

12. Viazis N, Sgouros S, Papaxoinis K, et al. Bowel preparation increases the diagnostic yield of capsule endoscopy: a prospective, randomized, controlled study. . 2004;60:534-538.

Gastroenterol

Endosc.

13. Barkin J, Friedman S. Wireless capsule endoscopy requiring surgical intervention: the world's experience [abstract]. 2002;55:S907.

Inflamm Bowel

Dis.

14. Kornbluth A, Legnani P, Lewis BS. Video capsule endoscopy in inflammatory bowel disease: past, present, and future. 2004;10:278-285.

Gastroenterol Nurs.

15. Scible SL, Anwer MB. Detecting a small bowel tumor via wireless capsule endoscopy: a clinical case study. 2004;27:118-120.

Answers:

1. A; 2. D; 3. C; 4. B; 5. A