Indications

Indications for VCE of the small bowel are listed in Box 104-1.

Obscure Gastrointestinal Bleeding

The source of GI bleeding remains unidentified in approximately 5% of patients and is thus referred to as obscure. Obscure GI bleeding may be overt, as evidenced by clinical signs (melena or hematochezia), or occult and manifested as positive fecal occult blood testing or IDA. By definition, obscure GI bleeding occurs when esophagogastroduodenoscopy (EGD) and colonoscopy are negative. In such cases, further work-up is required. The role of VCE in obscure GI bleeding has been validated in two meta-analyses and is outlined in Figure 104-1. In patients presenting with IDA, VCE has a less validated role (Fig. 104-2). As has been validated in the aforementioned meta-analyses, VCE is the most sensitive diagnostic modality and is considered the first line in the diagnostic work-up for obscure GI bleeding. Figure 104-3 shows an example of bleeding in the small bowel as captured by the Pillcam.

Figure 104-1 The diagnostic algorithm of obscure gastrointestinal hemorrhage. DBE, double-balloon enteroscopy; IOE, intraoperative enteroscopy; PE, push enteroscopy; VCE, video capsule endoscopy. *Some experts suggest a second-look endoscopy prior to capsule endoscopy to ensure that no pathology was missed.

Figure 104-2 The diagnostic algorithm of iron-deficiency anemia (IDA). EGD, esophagogastroduodenoscopy; VCE, video capsule endoscopy.

Figure 104-3 Active small bowel bleeding.

Crohn’s Disease

Crohn’s disease is an idiopathic inflammatory disease involving the small bowel in approximately 75% of cases. Because no diagnostic gold standard exists, the diagnosis of CD in the small bowel is based on clinical, endoscopic, radiologic, and histologic findings. However, available diagnostic modalities are neither sensitive nor specific. As a result, appropriate drug therapy may be delayed. Furthermore, available endoscopic procedures (e.g., push enteroscopy) fail to visualize the entire small bowel distal to the ligament of Treitz; thus, significant small bowel involvement may be missed. VCE has a role both in diagnosing suspected CD (Fig. 104-4) and in determining the extent of small bowel involvement in CD. VCE also has been shown to be more sensitive than other imaging modalities in detecting small bowel mucosal breaks and thus is very helpful in diagnosing early CD (Fig. 104-5) and in assessing mucosal healing after drug treatment and disease recurrence after surgery.

Figure 104-4 The role of capsule endoscopy in the diagnosis of Crohn’s disease. CTE, computed tomographic enterography; MRE, magnetic resonance enterography; SB CD, small bowel Crohn’s disease; SBFT, small bowel follow-through.

Figure 104-5 Small bowel Crohn’s disease. A, Aphthous ulcer. B, Inflammatory stricture.

The advent of VCE has resulted in a major shift in the diagnosis of small bowel tumors (Fig. 104-6). In the past, small bowel tumors were usually diagnosed only during the work-up of persistent abdominal pain or when obstructive symptoms appeared. Today, approximately 80% of small bowel tumors that are detected by VCE are from referrals to VCE due to obscure GI bleeding evaluation. The estimated prevalence of small bowel tumors in VCE for obscure bleeding is 6.3% to 12.3%. There is preliminary evidence that VCE favorably changes the clinical outcome in such cases. Note that when small bowel obstructive symptoms are present the initial work-up should be push enteroscopy or double-balloon enteroscopy rather than VCE.

Figure 104-6 Small bowel tumor.

Inherited Polyposis Syndromes

The lifetime risk of duodenal and small bowel tumors in familial adenomatous polyposis may be as high as 5% to 12%. Other polyposis syndromes, including Peutz-Jeghers syndrome and juvenile polyposis, also portend increased risk for small bowel and duodenal cancers, with a relative risk of 13% for small bowel tumors in Peutz-Jeghers syndrome. This risk has led to a recommended screening schedule including EGD or small bowel barium series every 1 to 3 years. VCE has been shown be a sensitive surveillance tool for detecting small bowel polyps in this high-risk population, with a reported sensitivity of over 90%.

Celiac Disease

Celiac disease has a prevalence of approximately 1% in the general population and is diagnosed by clinical suspicion, serologic and histologic findings obtained by small bowel biopsy ranging from partial to total villous atrophy, and patient response to a gluten-free diet. VCE, which provides a high-resolution magnified view of the small bowel mucosa, can detect mucosal changes such as scalloping, mosaic pattern, loss of normal villous architecture, loss of small bowel folds, and nodularity (Fig. 104-7). These findings by capsule endoscopy have been correlated with the typical histologic findings of celiac disease. Moreover, VCE has been shown to have good sensitivity and excellent specificity in the diagnosis of celiac disease even in a “real life” setting and in the detection of more subtle histologic changes. It appears that VCE has a role in the diagnosis of celiac disease when there is a strong clinical suspicion (typical symptoms or positive serology) and EGD with small bowel biopsy is either negative or inconclusive, or the patient does not tolerate or is unwilling to undergo EGD. Furthermore, when patients with diagnosed celiac disease on a strict gluten-free diet develop worrisome symptoms such as weight loss, anemia, fever, bleeding, abdominal pain, or recurrence of malabsorption, or when results of abdominal imaging are abnormal (except for stricture), VCE is indicated to evaluate for small bowel malignancy or enteropathy-associated lymphoma. However, the diagnosis of the typical injury pattern seen with VCE in celiac disease requires considerable expertise, and such patients probably should be referred to specialized centers.

Figure 104-7 Celiac disease: mucosal scalloping.

Monitoring Small Bowel Drug Effects or Side Effects

Several studies have shown that VCE is a sensitive tool to demonstrate small bowel injury caused by nonsteroidal anti-inflammatory drugs (NSAIDs). In fact, VCE can readily detect erythema, erosions, ulcerations, and weblike strictures caused by NSAIDs, even in asymptomatic subjects. There have also been recent reports on VCE being used to monitor response to immunosuppressive therapy to manage intestinal graft-versus-host disease.

Contraindications

Video capsule endoscopy is contraindicated for use under the following conditions (Box 104-2):

• Patients with known or suspected GI obstruction, strictures, or fistulas based on the clinical picture or preprocedure testing

• Patients with cardiac pacemakers, cardiac defibrillators, or other implanted electromedical devices

• Patients with swallowing disorders

Also, see the pertinent history in the Preprocedure Patient Preparation section.

Equipment and Overview of Video Capsule Endoscopy System

The capsule (Pillcam SB2; Given Imaging, Ltd.) is a disposable device (11 × 26 mm) composed of a light source, lens, metal oxide semiconductor imager, battery, and transmitter (Fig. 104-8). The capsule has a slippery coating that allows easy ingestion and transit with normal intestinal peristalsis. The capsule coating also prevents adhesion of luminal contents and obstruction of the visual field. The battery life is approximately 7 to 8 hours, during which two images per second are acquired and transmitted to a recording device worn by the patient (Fig. 104-9). The images are acquired through the optical dome, creating a visual field of 140 to 176 degrees and a magnification of 8 : 1. In total, 50,000 to 60,000 images are acquired and transmitted by a sensor array (8 sensors) located on the chest and abdominal wall of the patient to the recording device worn on the patient’s belt (see Fig. 104-9). After 7 to 8 hours, the recorder and sensors are removed from the patient and the images are downloaded into a reporting and processing of images and data (RAPID) computer workstation (Fig. 104-10). A continuous video movie is created. Additional features that are currently used include an approximate localization system for each image, a blood detector, an image magnifier, and simultaneous viewing of two to four images.