| Abstract|| |
Video capsule endoscopy (VCE) has recently been introduced to fill the gap between examinations of the upper and lower gastrointestinal tract, mainly to examine the small bowel (SB) for sources of obscure bleeding in addition to many other indications. VCE represents a minute endoscope, embedded in a swallowable capsule that is propelled by peristalsis and achieves the journey to the right colon in 5-8 hours. Images captured by the capsule are recorded on a hard drive attached to the patient's belt. Many studies have recently shown that the diagnostic yield of VCE is superior to that of push enteroscopy. This mini-review contains information on
the technical aspects, indications, safety and tolerance of VCE.
It is well known that radiological investigations of the small bowel (SB) have a limited diagnostic yield, are relatively invasive, and often lead to late discovery of diseases, especially malignancy and profuse bleeding, at a worse stage. Also, push enteroscopy is limited by the depth of the insertion of the instrument to the proximal jejunum and, in the retrograde, to the last 50-80 cm of the terminal ileum, with an ability to visualize the entire SB only in 10-70% of cases. Introduction of video capsule endoscopy (VCE) is therefore regarded a significant advance in investigating intestinal diseases, and closes the gap in evaluating the SB, "the black box" of endoscopy(1). This mini-review describes the current indications of VCE and the prerequisites for accurate examination, and briefly discusses its tolerance and safety.
Keywords: Small intestine; intestinal diseases; endoscopy; obscure digestive bleeding; push enteroscopy; wireless capsule endoscopy
|How to cite this article:|
Helmy A. Video capsule endoscopy and the hidden gastrointestinal diseases. Saudi J Gastroenterol 2006;12:90-2
| Description of the VCE|| |
The VCE (PillCam) is a biconvex device sealed in abiocompatible substance resistant to digestive fluids, small enoughto be swallowed (cylindrical in shape, 11x26 mm in diameter, and3.7 g in weight). It contains an optical device to capture images,a high frequency transmitter to transmit high quality imagesfrom the gastrointestinal tract to a connected data recorder, andbatteries powering them,. A complete VCE system consistsof 4 components, namely the single-use VCE, the sensor arraysfixed by tape on the patient's abdomen, a data recorder carried bythe patient on a belt and a computer workstation with advancedimaging software. The capsule is passively propelled through theintestine by peristalsis. The mean gastric and SB Transit is 63minutes (gastric; range 10-319 minutes) and 194 minutes (SB;range 70-322 minutes) respectively. The intestine is illuminatedthrough the optical dome by white light emitting diodes (LEDs).The acquired image is focused by a short focal aspherical lens onthe complementary metal oxide semiconductor (CMOS) camera[Figure - 1]. The capsule is powered by two silver oxide batterieswith an expected lifetime of eight hours. The capsule acquiresand transmits two images per second and delivers over 50,000images during an eight-hour procedure.
| The procedure|| |
The VCE procedure can be performed as outpatient, after 12hours fasting, and bowel cleansing as before colonoscopy.The capsule is then ingested after the patient carries the beltpack containing a power supply and the hard drive for archivingreceived images, and after applying 8 skin antennas, similar toECG electrodes, to his abdominal wall in a designated pattern andconnecting them to the hard drive. Swallowing of the capsuleis usually easy. However, in some patients with swallowingdisorders or in children, the capsule must be introduced in theduodenum with an endoscope, making the procedure moreinvasive. Patients are allowed to drink clear liquids 2 hoursafter ingestion of the capsule and to eat a light meal 2 hours later.During the 8 hours recording time, patients should record anyabdominal symptoms and check the blinking light on the beltpack for confirmation of signal reception. Then, the sensorarray and the data recorder are removed and the recorded digitalinformation is downloaded to the computer workstation over 3hours. The capsule is expulsed naturally, usually within 24-48hours. Reading time and interpretation of images requires onaverage of 40-60 minutes. Several features have been added tothe software used to read the capsule recording so as to help thereader locate the site of lesions and detect suspected blood, aswell as for the development of a multi-viewing video system.
| Indications|| |
The indications for a VCE examination of the SB are as multipleas the intestinal diseases [Table - 1], especially those difficult to beassessed by endoscopy. Initial reports demonstrated that VCEis at least as effective as push enteroscopy and, in most cases,more effective than it to detect such intestinal lesions. Obscuregastrointestinal bleeding (OGIB) is regarded as the 'natural' andmost important indication of the VCE, with a diagnostic yieldof 55-81%. The predictive value of the VCE result to diagnose(positive predictive value) and rule out (negative predictivevalue) an intestinal lesion is 72% and 93% respectively. A recentstudy by Pennazio et al, showed that the sensitivity of VCE todetect an intestinal lesion in patients with OGIB was 89% and itsspecificity is 95%.7
Investigation of patients with suspected non-steroidal antiinflammatorydrug (NSAID)-related intestinal lesions or familialpolyposis syndrome is also validated. The clinical pictureof NSAID-related lesions includes overt or occult bleeding,abdominal pain or intestinal obstruction. Therefore, a CT-scanfor assessment of the SB may be worth doing before ingestingthe VCE. Lesions most frequently found are ulcers and erosionsand there is no correlation between the presence of gastric lesionsand intestinal lesions. VCE and MRI were found to be equalin detecting polyps larger than 15 mm, while VCE detected morefrequently those between 5 and 15 mm and only VCE detectedpolyps smaller than 5 mm in the entire SB except those locatedin the area of papilla, Therefore, a duodenoscopy with alateral view remains thus the best duodenal examination for suchpapillary polyps.
VCE might also become useful for the diagnosis of smallintestinal Crohn's disease and undetermined colitis. Currentliterature indicates that VCE detects intestinal lesions in a largegroup of patients with known or suspected Crohn's disease, witha diagnostic yield superior to that of other imaging modalities.However, lesions detected by VCE, e.g. ulcers or erosions, arenot specific to Crohn's disease in the absence of pathologicalexamination. Therefore, detection of such lesions in a patientwith known Crohn's disease in other locations will significantlymodify the therapeutic approach. In addition, CVE should beuseful in assessing disease recurrence in patients with Crohn'sdisease in remission. Clinical trials are currently undertaken tovalidate these strategies. However, the benefit expected fromVCE examination in a patient with known or suspected Crohn'sdisease must be weighed with the risk of blockage of theprogression of the capsule .
VCE is currently under evaluation for the diagnosis and longterm surveillance of patients with Celiac disease, in order to detectthe occurrence of complications,. Other potential indicationsof VCE include patients with unexplained abdominal pain,hypobetalipoproteinemia, gastro-intestinal graft-versushostdisease, and Whipple's disease,. VCE is also underinvestigation in the diagnosis of lesions in other gut segments suchas the esophagus, stomach, and caecum,,. In pediatrics, VCEis considered safe in children aged nine years or over. The mainindications are diagnosing celiac disease, investigating childrenwith OGIB or suspicion of familial polyposis syndromes, andin those with suspected of Crohn's disease not demonstrated byother modalities.
| Tolerance and safety|| |
Overall tolerance of VCE by the patients is satisfactory.VCE is contraindicated in patients with known or suspectedgastrointestinal obstruction, narrowing, fistula or swallowingdisorders. The presence of a cardiac pacemaker, defibrillatoror other electromedical implanted device was previouslyregarded as a contraindication. However, recent data suggestthat the radio-frequency signal of VCE does not interfere withcardiac pacemakers. Safety in pregnancy has not yet beenestablished,. Blockage of VCE progression within the SBhas been reported in up to 4% of cases in some studies,.especially patients with Crohn's disease. Prolonged residency orretention of the capsule in the stomach may occur in patients withdiabetes and gastroparesis. This may require interventions in theform of endoscopic push-down, endoscopic retrieval, or surgery.Therefore careful assessment of the medical history (previoussurgeries, use of NSAIDs and radiotherapy) is recommended and,in patients with a suspicion of a stenosis, radiological assessmentof the SB should be performed. Furthermore, this blockage riskshould be explained to patients before the procedure includingthe consequences (surgical or endoscopic extraction). Asblockage of the capsule by an unknown stenosis of the gut isthe most concerning complication in patients undergoing VCE,and because radiological imaging techniques do not accuratelydetect such stenosis, a system that consists of an ingestible anddissolvable capsule that contains a small Radio Frequency ID tagthat can be detected by a hand-held scanner, containing bariumthat allows fluoroscopic localization of the obstruction, wasdesigned, and needs further clinical evaluation.
| Concluding Remarks|| |
VCE is a well tolerated and safe examination of the SB. Thediagnostic yield of VCE is constantly superior to radiologicalinvestigations and push-enteroscopy. Patients with OGIB are theprimary and best validated indication. VCE must be performedas soon as possible after the bleeding episode in patients with anantecedent of overt bleeding. Further well-designed studies arerequired to evaluate the role of VCE in surveillance of patientswith celiac disease, Crohn's disease and Whipple's disease, andto evaluate the clinical relevance of the combining VCE andDouble Balloon Enteroscopy for investigating patients withsmall intestinal diseases and, finally, to explore the usefulness ofthe VCE in other gut segments.
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Department of Liver Transplantation, MBC: 72, PO Box: 3354, Riyadh 11211
Source of Support: None, Conflict of Interest: None
[Figure - 1]
[Table - 1]