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Capsule endoscopy is a medical procedure used to record internal images of the
gastrointestinal tract for use in
disease diagnosis. Newer developments are also able to take biopsies and release medication at specific locations of the entire gastrointestinal tract. Unlike the more widely used endoscope, capsule endoscopy provides the ability to see the middle portion of the small intestine. It can be applied to the detection of various
gastrointestinal cancers,
digestive diseases
Gastrointestinal diseases (abbrev. GI diseases or GI illnesses) refer to diseases involving the gastrointestinal tract, namely the oesophagus, stomach, small intestine, large intestine and rectum, and the accessory organs of digestion, the live ...
, ulcers, unexplained bleedings, and general abdominal pains. After a patient swallows the capsule, it passes along the gastrointestinal tract, taking a number of images per second which are transmitted wirelessly to an array of receivers connected to a portable recording device carried by the patient. General advantages of capsule endoscopy over standard
endoscopy
An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inse ...
include the minimally invasive procedure setup, ability to visualize more of the gastrointestinal tract, and lower cost of the procedure.
History
Capsule endoscopy was first conceptualized by Israeli engineer
Gavrial Iddan and Israeli gastroenterologist Eitan Scapa in Boston, MA in the early 1980s. The two partners first developed a CCD (
charged coupled device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are ...
) camera-based imaging system using a fiber-optic tether. This initial design suffered from high power consumption and slow transmission times of image data of at best 10 minutes. In 1993 Iddan had the idea to split the system into three components, the camera and transmitter, the recorder attached to a sensor array on the patient's abdomen, and a software package that processes the stored data at leisure by a physician at a later time. This new setup was made possible by the replacement of the CCD camera with a CMOS (
complementary metal-oxide-semiconductor) camera. These cameras consume just one percent of the energy of their CCD counterparts. The more efficient power system allowed for the removal of the fiber optic cable for a stand-alone imaging system. This three-component imaging system remains popular today.
In 2001 the FDA (
Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
) approved the first capsule endoscope developed by
Given Imaging
Given Imaging (Hebrew: גיוון אימג'ינג) is an Israeli medical technology company that manufactures and markets diagnostic products for the visualization and detection of disorders of the gastrointestinal tract. Until March 2014, it was ...
for use in patients. Many new models such as the PillCam SB and DBE for obscure gastrointestinal bleeding, the Olympus CE for the small bowel, the PillCam ESO for investigation of esophageal diseases, and the PillCam COLON for detection of colonic neoplasias have been created.
As research into capsule endoscopy has increased and technology has advanced better wireless and more energy-efficient systems have allowed for the creation of more compact capsules and image processing systems ,with many in development today.
Technology
Capsule endoscopy uses a small vitamin-sized wireless camera to capture images of a patient’s digestive tract. The capsule is generally composed of a camera, antenna, and light array. Due to the small nature of the device images can not be stored within it. As a result, a sensor array with a storage unit is placed on the abdomen of the patient for the imaging period. This storage unit can then be connected to a computer at a later time so that a medical professional can analyze the images.
Newer models of the capsule endoscope have looked to add camera systems on both ends of the pill or even store images within the pill itself to minimize the amount of medical equipment one must carry with them while using the device.
For systems that store images directly within the pill, the pill must be collected after excretion for extraction of the images by a secondary device.
The main shortcoming of capsule endoscopy is the
field of view
The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation.
Human ...
. Depending on the placement of the camera system within the device images may become obstructed by folds in the digestive tract. Due to the passive nature of image capture and lack of control in maneuvering the device through the digestive tract novel solutions are being developed by various companies and research labs. For systems that utilize the setup with the camera system at the end of the capsule, the field of view ranges from 140 to 170 degrees.
There are several advantages to choosing to use capsule endoscopy over standard
endoscopy
An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inse ...
. Standard endoscopy can be more uncomfortable for a patient, can be more prone to puncturing the digestive tract walls, and is not able to access the middle portion of the small intestine. Endoscopes must enter either through the mouth/nasal cavities or the rectum. Due to restrictions in length, extremely important regions for diagnosis in the small intestine are not able to be accessed. Currently, within the United States, capsule endoscopy can not be used as a primary imaging method over standard endoscopy first. As a result, many patients must first undergo standard endoscopy to then be referred for capsule endoscopy. Further innovation will be required to make capsule endoscopy comparable to the current standard of care, but extensive work is being performed to achieve this.
Medical uses
Esophagogastroduodenoscopy (EGD), employs a camera attached to a long flexible tube to view the upper portion of the gastrointestinal tract, namely the
esophagus
The esophagus ( American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to ...
, the
stomach
The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...
, and the beginning of the first part of the
small intestine called the
duodenum. A
colonoscope
Colonoscopy () or coloscopy () is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It can provide a visual diagnosis (''e. ...
, inserted through the
rectum, can view the
colon and the distal portion of the small intestine, the terminal
ileum
The ileum () is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine m ...
. These two types of endoscopy however cannot visualize the majority of the middle portion of the small intestine.
Capsule endoscopy is therefore used to examine parts of the gastrointestinal tract that cannot be seen by standard endoscopy. It is useful when the disease is suspected in the small intestine, and can sometimes be used to find the site of
gastrointestinal bleeding
Gastrointestinal bleeding (GI bleed), also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a short time, symptoms may include ...
or the cause of unexplained abdominal pain, such as
Crohn's disease. However, unlike EGD or colonoscopy, it cannot be used to treat pathology that may be discovered. Common reasons for using capsule endoscopy include diagnosis of unexplained bleeding, iron deficiency, or abdominal pain, searching for polyps, ulcers, and tumors of the small intestine, and diagnosis of
inflammatory bowel disease.
The images collected by the miniature camera during a session are transferred wirelessly to an external receiver worn by the patient, using any one of a band of appropriate frequencies. The collected images are then transferred to a computer for display, review, and diagnosis. A transmitted radio-frequency signal emitted by some capsules can be used to accurately estimate the location of the capsule and to track it in real-time inside the body and gastrointestinal tract. Capsule endoscopy can still not yet replace standard endoscopy for various diseases, as is the case for those with
cirrhosis
Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue rep ...
.
As of 2014, research was targeting additional sensing mechanisms and localization and motion control systems to enable new applications for the technology, for example, drug delivery. Wireless energy transmission was also being investigated as a way of providing a continuous energy source for the capsule.
Procedure
Capsule endoscopy requires a number of different preparatory procedures to ensure clear images are taken of a patient's gastrointestinal tract for an accurate diagnosis of disease. There are various types of capsule endoscopes, but for a generalized description, one can assume the most common setup requires the capsule, sensor array, storage unit, and computer system being used. First, a patient will need to have the sensor array placed on their abdomen with a recording unit worn as a belt. The patient may be asked to stay at the hospital or return home depending on the start time. Next, the pill must be swallowed by the patient. After approximately 8 hours the sensor array can be removed and returned to a physician. The capsule will be excreted through regular bowel movements.
During the procedure, there are a number of different policies to follow. A patient should only drink clear liquids for the first two hours after swallowing the pill and may eat after 4 hours. MRI studies, ham radios, metal detectors, and strenuous physical activity should all be avoided. Additionally, all external equipment must be kept dry.
Manufacturers
As of 2022, there are a number of manufacturers who produce capsule endoscopes.
The technology was originally developed by Israeli scientists,
Gavriel Iddan
Gavriel Iddan is an Israeli electro-optical engineer and the inventor of wireless capsule endoscopy. Initially at RAFAEL Armament Development Authority working on guided missile technology, Iddan got the idea for an endoscopic capsule while on s ...
and Eitan Scapa, with the first pill swallowed in 1997;
Iddan founded
Given Imaging
Given Imaging (Hebrew: גיוון אימג'ינג) is an Israeli medical technology company that manufactures and markets diagnostic products for the visualization and detection of disorders of the gastrointestinal tract. Until March 2014, it was ...
in Israel which received FDA approval in 2001.
Medtronic today produces one of the more widely used capsule endoscope systems called the PillCam having sold over 3.5 million units. Medtronic purchased the PillCam system from Given Imaging in 2014.
Side effects
Capsule endoscopy is considered to be a very safe method for gastrointestinal tract examination. The capsule is usually excreted with a patient’s
feces within 24–48 hours after ingestion. There has been a single report of retention of the capsule lasting almost four and a half years although the patient was asymptomatic. However, the risk of bowel obstruction may be countered by an abdominal X-ray to locate the device for removal by endoscopy or surgery.
Risk of retention
In a review of 22,840 cases, the capsule was retained 1.4% of the time, with
Crohn's disease a common cause; most were surgically removed.
The rate of capsule retention varies by the indication for the procedure, with the highest rate seen with known Crohn's disease (5-13%), followed by obscure gastrointestinal bleeding (1.5%), suspected Crohn's disease (1.4%), and healthy volunteers (0%).
Risk factors for capsule retention include Crohn's disease, NSAID use, and abdominal radiation.
References
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Endoscopy
Diagnostic gastroenterology
Israeli inventions
21st-century inventions