Surveillance of Bleeding Peptic Ulcer Using Wireless Capsule Endoscopy

Background

Acute gastrointestinal bleeding is a common medical emergency worldwide. In Hong Kong it accounts for about 5% of all admissions through the Accident and Emergency Department1. The most common cause is bleeding from a peptic ulcer.

Ulcers bleed when an artery at the base of the ulcer is eroded, Bleeding from such an eroded artery may be intermittent, as the artery may be plugged by a thrombus. Dislodgement of the clot results in rebleeding. Rebleeding has long been recognized as one of the worse prognosticators for ulcer bleeding and is associated with a 6-10 fold increase in mortality. Rebleeding is associated with a major bleed manifested by hematemesis and hypotension, indicating that a large size vessel has been eroded. Such vessels, and the clot plugging them, may be visible endoscopically and have been named "stigmata of recent haemorrhage". Such stigmata are associated with a higher risk of rebleeding. High-risk stigmata, such as active bleeding, a protuberant "visible vessel", or an adherent clot, are now used to select patients who are liable to rebleed for endoscopic therapy. In recent years, with advances in endoscopic technology and expertise, therapeutic endoscopy has taken over as the first line therapy for bleeding5. Techniques such as injection therapy, thermal coagulation and clip application have been shown to be highly effective in controlling bleeding7.

Rebleeding after endoscopic therapy

Rebleeding is the most important prognostic factor in patients with ulcer haemorrhage. It carries a 10-fold increase in mortality. Rebleeding can be predicted by hematemesis and shock on admission. Before the era of therapeutic endoscopy traditional dogma recommends early surgery to preempt another catastrophic bleed in these patients. With the advent of effective endoscopic haemostasis the place of early surgery is less clear. Indeed a trial at our center indicates that repeat endoscopic therapy can salvage 75% of rebleeding patients without compromising patient safety10.

Scheduled repeat endoscopy at 24 hour intervals have been used to detect and retreat any remaining stigmata11. Such a policy also subjects many patients to unnecessary endoscopy and treatment but has not been shown to improve outcome. Re-endoscopy at 24-hour intervals misses rebleeding that occurs in the interim, but repeated endoscopy at closer intervals is impractical. Some authors has suggested combining clinical endoscopic data in a scoring system to select patients for repeat endoscopic re-treatment, and demonstrated improved outcome in a small series. Others have used Doppler signals in arteries in the ulcer base to predict failures of endoscopic treatment.

Recognition of rebleeding - Use of wireless endoscopy

Clinical rebleeding is usually defined as vomiting of red blood, hemodynamic instability or drop in the hemoglobin level after initial stabilization. These clinical features appear only after a significant amount of blood has been lost. There is, at present, no reliable method of detecting rebleeding in a timely fashion. If there is a reliable early warning system, analogous to ECG monitoring for arrhythmia in patients who has had a myocardial infarction, we may be able to intervene in time to preempt the harmful effects of further major blood loss in a patient who has already bled from the ulcer.

Endoscopy using a pill sized (11mm x 26mm, weight ~ 4 grams) capsule endoscope was first reported by Iddan. The capsule can be swallowed and transmit images from various part of the gastrointestinal tract as the capsule traverses the gastrointestinal tract. The main indication at present is the visualization of the small intestine, especially for locating sources of bleeding that are beyond the range of gastroscopy and colonoscopy. The battery of the capsule lasts for up to 8 hours.

We aimed to use the capsule endoscope to monitor the bleeding peptic ulcer after therapeutic endoscopy in order to detect rebleeding before clinical manifestation.