Video capsule endoscopy (VCE) has completed the endoscopic visualization of the entire luminal gastrointestinal tract. VCE can be performed in inpatients and outpatients, requires appropriate bowel preparation before the study, and can be administered via oral swallowing or endoscopic device placement into the small bowel based on outlined patient-dependent factors. Current commercially available VCE systems were reviewed and compared for individual features and attributes. This article focuses on preparation for VCE, currently available VCE technology, how to read a VCE study, and risks and contraindications to VCE.
Key points
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Video capsule endoscopy can be performed in inpatients and outpatients, requires appropriate bowel preparation before the study, and can be administered via oral swallowing or endoscopic device placement into the small bowel based on outlined patient-dependent factors.
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Current commercially available video capsule endoscopy systems were reviewed and compared for individual features and attributes.
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Reading a video capsule endoscopy study should be done in a systematic manner, including identification of anatomic landmarks, calculation of small bowel transit time, objective assessment of the quality of bowel preparation, and detailed description of any abnormal findings.
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There are multiple contraindications and risks to video capsule endoscopy, which need to be carefully weighed with an appropriate informed consent process between patient and provider.
Introduction
Video capsule endoscopy (VCE) has completed the endoscopic visualization of the entire luminal gastrointestinal tract. It has taken us on a “fantastic voyage,” which is improving with each technical advance. Knowledge of its indications, preparation, and contraindications will allow us to apply this endoscopic technology in a precise and accurate manner. This article focuses on preparation for VCE, currently available VCE technology, how to read a VCE study, and risks and contraindications to VCE.
Introduction
Video capsule endoscopy (VCE) has completed the endoscopic visualization of the entire luminal gastrointestinal tract. It has taken us on a “fantastic voyage,” which is improving with each technical advance. Knowledge of its indications, preparation, and contraindications will allow us to apply this endoscopic technology in a precise and accurate manner. This article focuses on preparation for VCE, currently available VCE technology, how to read a VCE study, and risks and contraindications to VCE.
Video capsule endoscopy: preparation, administration, and completion
VCE can be performed in both inpatients and outpatients. Patients are generally recommended to remain on a clear liquid diet the day before VCE administration. A 2009 meta-analysis of 12 studies by Rokkas and colleagues demonstrated the importance of bowel preparation in comparison to clear liquid diet to improve small bowel visualization quality and to increase the diagnostic yield of VCE examinations. Bowel preparation with 2 L of polyethylene glycol is common and provides relatively comparable preparation quality and diagnostic yield to a 4-L polyethylene glycol preparation. Newer low-volume bowel preparations using MoviPrep or Pico-Salax have also been suggested to have comparable efficacy. Simethicone may be administered before VCE to reduce the presence of bubbles in the small bowel.
Narcotics and other medications such as anticholinergics and antihistamines, which may cause gastroparesis, should be stopped if possible 2 to 3 days before VCE administration. Alternatively, patients can receive either metoclopramide 10 mg 3 times daily before meals or erythromycin 250 mg every 8 hours for 2 to 3 days before VCE administration; however, endoscopic placement may be needed given potential medication-induced gastroparesis. Cessation or dose reduction of anticoagulants, including warfarin or the novel anticoagulants, is not recommended before VCE administration, and diagnostic yield of VCE may actually be increased if bleeding is provoked during the study.
VCE administration can be performed using 2 methods: swallowing the VCE by mouth or endoscopic deployment of the VCE into the small bowel. Oral VCE administration is more common, with obvious benefit by foregoing an additional invasive procedure with all associated risks, and marked cost savings of the endoscopic procedure and sedation. Following oral VCE administration, patients may ingest clear liquids 2 hours later and may have a light meal 4 hours after VCE administration. Failure to reach the cecum during the recorded time resulting in an incomplete study is estimated to occur in up to 19% to 27% of patients undergoing VCE via oral administration. A portion of these patients may be able to achieve a complete VCE study with endoscopic deployment.
Endoscopic deployment should be considered in patients with known or anticipated difficulty of the VCE passing from the mouth to the small bowel in a safe and timely manner to enable maximal small bowel mucosal visualization and to ensure a complete capsule study. These factors include patients with known inability to swallow (oropharyngeal, esophageal, or both, such as after a cerebrovascular accident, musculoskeletal disorders, poor nutrition with undiagnosed dysphagia, and known dysphagia), gastroparesis, opioid usage with delayed gastric transit, hospitalized patients, especially those who are bedbound and patients in the intensive care unit, and those with prior capsule failing to reach the cecum. Although increasingly common, patients with prior bariatric or gastric surgery may satisfactorily undergo oral VCE administration with similar completion rates to the general population.
Lack of physical activity such as in patients who are on strict bed rest is significantly associated with an incomplete VCE study compared with those who are ambulatory or with mild bed rest. Real-time viewer features found on certain capsule devices may assist the endoscopist in the placement of the capsule device into the duodenum in particularly challenging cases. Despite endoscopic placement, there still remains a subset of patients in whom VCE may be incomplete, perhaps due to underlying structural or motility disorders. Importantly, endoscopic sedation with propofol on the same day as VCE increases small bowel transit time (SBTT), but does not affect VCE completion rates.
Prokinetic agents may be used to promote VCE exit from the stomach into the small bowel in patients undergoing oral capsule administration and should be considered in inpatients or those with limited mobility. A dose of metoclopramide 10 mg can be given either by endoscopy unit protocol after oral VCE administration or by examination of a real-time viewer at a set point such as 30 to 60 minutes after oral VCE administration to determine if the VCE remains in the stomach. Although metoclopramide is the most common prokinetic used, erythromycin and domperidone administration with VCE may result in a slightly higher completion rate to the cecum for the study, but no tangible effect on diagnostic yield of the VCE study.
Video capsule endoscopy systems
There are 5 commercially available VCE systems, with corresponding individual software programs for reading the recorded study images. Each system has unique features, which are aimed to address the inability to control VCE movement, to increase completion rate of a VCE study, and ultimately improve diagnostic yield ( Table 1 ).
| PillCam SB3 | EndoCapsule 10 | CapsoCam SV1 | MiroCam | OMOM | |
|---|---|---|---|---|---|
| Manufacturer | Given Imaging | Olympus | CapsoVision | IntroMedic | Jianshan |
| Length (mm) | 26 | 26 | 31 | 24.5 | 28 |
| Diameter (mm) | 11 | 11 | 11 | 10.8 | 13 |
| Weight (g) | 1.9 | 3.3 | 4 | 3.25 | |
| Type of image sensor | CMOS | CCD | CMOS | CMOS | CMOS |
| Frame rate (per second) | 2–6 (adaptive frame rate) | 2 | 20 (5 per camera) first 2 h then 12 (3 per camera) thereafter | 3 | 2 |
| Number of cameras | 1 | 1 | 4 | 1 | 1 |
| Field of view (°) | 156 | 160 | 360 | 170 | 140 |
| Battery life (h) | 12 | 12 | 15 | 12 | 8 |
PillCam SB1, SB2, SB3
The PillCam (Given Imaging Ltd, Yoqneam, Israel) was the first commercially available VCE system approved in the United States in 2001. Since then, there have been 3 generations of the PillCam, with most institutions currently using the SB2 or SB3 capsule systems. The PillCam SB2 system is approximately 26 × 11 mm in size and 3.45 g in weight, whereas the PillCam SB3 system is the same size but weighs 1.9 g. The SB2 captures 2 frames per second, using a complementary metal-oxide semiconductor for image capturing, and 6 white light–emitting diodes for illumination. Increasing frame rate from 2 to 4 frames per second has been examined in a study of 89 patients comparing the PillCam SB2 and the PillCam SB2 4 systems, which showed no significant clinical impact from the increased frame rate and increased overall reading times, but may have additional benefit in some selected situations to better visualize a lesion. The newer generation SB3 system has a 156° field of view, and an adaptive frame rate of 2 to 6 frames per second. More pictures are taken per second when the capsule is moving quicker and less as the capsule is moving slower, which may reduce duplication of images and therefore reading time. The original PillCam SB2 system has an 8-hour battery life, whereas newer models including the SB3 have increased battery life up to 12 to 15 hours. Images are transmitted from the device to a receiver band using radiofrequency, and the SB2 and SB3 models also have a small screen on the recorder for real-time viewing.
The accompanying PillCam Rapid Reader software includes the “Quick View” mode, which is an informatics algorithm that can shorten reading time while also attempting to increase diagnostic yield. Furthermore, the Rapid Reader viewing software also enables reviewer-controlled playback speed and number of images (1, 2, 4, or collage; although the collage mode is not intended for reading). There is an accompanying digital image atlas, and the “Suspected Blood Indicator” feature by which certain images with a cluster of red-colored pixels that may indicate blood or a lesion are highlighted. The “Suspected Blood Indicator” feature may further alert a reader to an area of concern. However, its utility in identifying lesions is limited, and therefore, it should not be relied on as a reading tool.
Endocapsule
The Endocapsule (Olympus Corporation, Tokyo, Japan) was the second commercially available VCE system, entering the market in 2008. The newest generation of this system, the Endocapsule 10, captures 2 frames per second of a 160° field of view and is of similar size at 26 × 11 mm and weight to other systems. This system uses 6 white light–emitting diodes for illumination, a charge coupled device for image sensing, and radiofrequency for transmitting images from the device to the receiver. It has up to a 12-hour battery life, and a real-time viewer on the receiver. The newest version of accompanying reading software has a 3-dimensional (3D) tracking function designed to track capsule progress through the small intestine and denotes this on each thumbnail picture, and automatic features to detect and remove poor quality images that would be unable to be read to expedite reviewing time. Furthermore, the reading software is equipped with an overview function, and both an express-selected mode and an auto-speed-adjusted mode to reduce redundant images, with the goal of decreased reading times while still maintaining diagnostic yield.
CapsoCam
The CapsoCam SV-1 (CapsoVision Inc, Saratoga, CA, USA) system entered international markets beginning in 2012 and was approved in the United States in 2016. It incorporates 4 laterally placed cameras facing the digestive wall offering 360° of viewing, without forward and backward viewing. Five frames per camera per second of images (20 frames/s in total) are taken in the first 2 hours of recording and then 3 frames per camera per second (12 frames/s in total) are taken thereafter. It has a maximal recording time of 15 total hours based on battery life. This specific capsule is 11 × 31 mm in size and 4 g in weight, has a complementary metal-oxide semiconductor in each camera, and uses 16 white light–emitting diodes, with an auto illumination controller to optimize light settings. It uses “Smart Motion Sense” technology to only activate the cameras when the capsule is moving, thereby reducing redundant images and saving battery life. Since 2012, there have been 2 subsequent generations of CapsoCam, although SV-1 remains the only US Food and Drug Administration–approved CapsoCam system in the United States currently. Of note, the CapsoCam stores images on board the device itself and does not transmit images to any external recording device. Therefore, patients must collect the capsule using a collecting pan and a magnetic wand and then return the device for downloading. Reading is performed using a 4-image viewer on the software with frequency of approximately 8 frames per second (total speed 32 frames/s based on 4 simultaneous image viewing). Furthermore, visualization of the ampulla has been reported at 71% in one series, which may positively impact diagnostic yield in the future.
MiroCam
The MiroCam capsule (IntroMedic, Seoul, Korea) captures 3 frames per second, with a 170° field of view, using a complementary oxide silicone chip for imaging, and measures 10.8 × 24.5 mm in size, and approximately 3.25 g in weight. This device does not use radiofrequency transmission and instead transmits recorded images using electric-field propagation by using 2 gold plates on the capsule surface in order to transmit low-voltage signals through the human body and to record electrodes attached to the skin, thereby decreasing power requirements and increasing video recording time to a total of 11 to 12 hours.
OMOM
The OMOM system (Jianshan Science and Technology Group Co, Ltd, Chongqing, China) is the last commercially available VCE system. It measures 13 × 28 mm in size, has a 140° field of view, captures images at 2 frames per second using a complementary metal-oxide semiconductor, and has an 8-hour battery life. This system is accompanied by reading software with a “Similar Pictures Elimination Mode” intended to decrease the reading time required for a study. In a study of 200 patients undergoing OMOM VCE, using level 1 (low) “Similar Pictures Elimination Mode,” there was similar sensitivity of the study compared with the conventional mode; however, there was a marked decrease in sensitivity when increasing to levels 2 or 3 (medium or high).
Comparison of Video Capsule Endoscopy Systems
There are multiple studies comparing the diagnostic yield of different VCE systems. The primary limitation of all of these studies is the emergence of newer versions of each VCE system after publication. Therefore, no specific conclusions can be drawn favoring one VCE system over another, but rather each system will have its own attributes and limitations, which should be weighed by the individual provider when deciding which system is most ideal for each institution.
The original generation PillCam SB1 and Endocapsule systems were compared in a total of 51 patients undergoing tandem VCE studies for obscure gastrointestinal bleeding, which showed a comparable diagnostic yield between the 2 VCE systems. In a study of 60 patients undergoing tandem VCE for obscure gastrointestinal bleeding with PillCam SB2 (Given Imaging) and the 4-camera CapsoCam SV-1 (CapsoVision), there was comparable identification of positive patients (84.8% PillCam SB2 vs 81.8% CapsoCam SV-1; P = .791), although CapsoCam SV-1 did detect significantly more lesions overall (108 vs 85; P = .001).
Again using a tandem approach, the PillCam SB2 and MiroCam were compared in 2 studies of 105 and 83 patients for obscure gastrointestinal bleeding, which found reasonable concordance rates for positive findings among both capsule subtypes, but a significantly longer duration of video for MiroCam than PillCam SB2. The MiroCam and Endocapsule systems have been compared in 50 patients undergoing VCE for a variety of indications, showing no significant differences in terms of completion rate of study to cecum and of diagnostic yield. Even with moderate concordance for diagnostic yield, both systems had several missed findings.
Additional Video Capsule Endoscopy Hardware and Software Features
Standard VCE devices have traditionally recorded approximately 8 hours of video. More recently, newer generations of some VCE systems have increased recording times from 8 hours up to 12 to 15 hours, with a resulting increase in completion rate of VCE reaching the cecum by between 4% and 8%, although no significant change in diagnostic yield of the study. The importance, however, of a complete VCE study cannot be overemphasized because it provides certainty of diagnosis to both the patient and the provider. Even with a complete VCE study, VCE may still miss 20% to 30% of lesions, and VCE may need to be repeated if the study is incomplete or reported as normal but with high clinical suspicion for ongoing small bowel abnormality.
Currently, there are commercially available, externally controlled VCE systems. The MiroCam Navi (IntroMedic) is able to be maneuvered using extracorporeal magnets to control VCE movement through the stomach and enable improved gastric visualization. The goal of this type of system is to potentially serve as a substitute for endoscopic evaluation of the stomach. These systems are not designed to be able to provide VCE control of movement through the small bowel.
Enhancements to software reading programs to improve diagnostic yield have also been proposed. Similar to chromoendoscopy that is used for lesion enhancement in the colon during colonoscopy, efforts have been made to develop forms of virtual chromoendoscopy to highlight lesions in the small bowel. These image processing algorithms include a flexible spectral imaging color enhancement and use a blue filter as part of the Rapid software with PillCam. Some of these programs have shown promise, but further study of this type of image processing overall is needed before consideration for widespread adoption in conventional VCE reading.
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