Capsule Endoscopy (Camera Pill)
Capsule Endoscopy (Camera Pill)
A test called capsule endoscopy (swallowing a small, pill-sized camera) is also being studied, but it is not yet recommended for standard screening at this time. It is used to look at the small intestine.
What is capsule endoscopy?
In 2000, a group of doctors from England reported the use of a new instrument for determining the causes of small bowel bleeding. The device, the capsule endoscope, is 1-1/8 inches long and 3/8 inches wide (26 mm x 11 mm), the size of a large pill. It is composed of a battery with an 8-hour lifespan, a strong light source, a camera, and a small transmitter. Once swallowed, the capsule begins transmitting images of the inside of the esophagus, stomach and small bowel to a receiver worn by the patient. The capsule takes two pictures per second, for a total of approximately 55,000 images. After 8 hours, the patient returns the receiver to the doctor who downloads the information to a computer and then can review in detail the 8 hours of pictures of the capsule passing through the intestine, looking for abnormalities that are possible sources of bleeding. The patient passes the capsule through the colon and it is eliminated in the stool and discarded. The capsule is generally safe and easy to take, however, the capsule can get stuck in the small intestine if there has been prior abdominal surgery causing scarring or other conditions that cause narrowing of the small intestine. If the capsule becomes stuck, endoscopic or surgical removal is necessary. In about 15% of exams, the capsule does not view the entire small bowel prior to the battery running out and may need to be repeated.
Like x-rays, the capsule is purely diagnostic and cannot be used to take biopsies, apply therapy, or mark abnormalities for surgery. Moreover, the capsule cannot be controlled once it has been ingested, so that once it has passed a suspicious abnormality, its progress cannot be slowed to better visualize the area. Despite these limitations, capsule endoscopy is frequently the test of choice for finding a source of small bowel bleeding if standard endoscopy has failed to do so.
How effective is capsule endoscopy at detecting the source of small bowel bleeding?
In an initial study, investigators showed that the capsule was better than routine endoscopy or enteroscopy at locating small beads that had been implanted into an animal's intestine. Other studies have shown the capsule is more effective than small bowel x-rays at finding the cause of bleeding. In 2001, the first human studies reported that capsule endoscopy not only found all of the bleeding sources seen using standard endoscopy, but also an additional bleeding cause in 56% of patients for whom traditional endoscopy had not been successful. Overall, in cases of what is known as occult bleeding (blood is microscopically present in the stool, but the stool looks normal), capsule endoscopy finds a potential source of bleeding in up to 67% of patients. In cases of overt bleeding (blood is seen in the stool or the stool is black and tarry as a result of digested blood), the results are highly variable. If the bleed happened in the past, the yield may be as low as 6%. If, however, the doctor believes that there is active bleeding occurring at the time of the test, the yield is >90%.
Learn more about Capsule Endoscopy at American Society for Gastrointestinal Endoscopy (ASGE)