Dr Carretero is a gastroenterologist with an interest in capsule endoscopy, having been involved in several colon capsule endoscopy trials. She is also the coordinator of the capsule endoscopy and enteroscopy group of the Spanish society of gastrointestinal endoscopy.
Dr Sidhu is a gastroenterologist with an interest in the small bowel and runs a tertiary capsule endoscopy and DAE service. She is also the first author of the BSG guidelines and co-author of the ESGE guidelines on small bowel endoscopy.
Capsule endoscopy (CE) is a non-invasive device intended for small bowel and/or colonic study. It consists of a small, swallowable, wireless, pill-sized camera that allows direct visualisation of the gastrointestinal (GI) mucosa.
The design of the capsule is different depending on the part of the GI tract to be studied. The small bowel capsule has one optical dome, and it is generally used in patients with suspected bleeding or to identify evidence of active Crohn’s disease; the colon capsule has two optical domes and a higher frame rate, and it can be considered as an alternative to conventional colonoscopy, especially for cases of incomplete colonoscopy. There is also a new capsule with two optical domes designed for the pan-endoscopic study of both the small bowel and colon.
The main characteristic of this device is the wireless technology, that makes it a very well tolerated procedure. However, this feature is also one of its drawbacks, as it cannot be controlled by the physician. The capsule moves through the gut depending on the intestinal movements, and the reader is not able to drive it back and forth or to stop the capsule to look more carefully at any finding. Even more, the visualisation depends on the intestinal cleansing level, as rinsing water and aspiration is not possible.
Capsule endoscopists should be aware of these characteristics, as they directly affect the reading and diagnosis.
© UEG 2018 Carretero and Sidhu.
Cite this article as:
Carretero C and Sidhu R. Mistakes in capsule endoscopy and how to avoid them. UEG Education 2018; 18: 21–23.
Correspondence to:
Conflicts of interest:
The authors declare there are no conflicts of interest.
Published online:
July 19, 2018.
Reviewed: July 2024.
The ampulla is visualised in approximately < 20% of CE videos.1 In a small proportion of patients, the capsule re-enters the stomach (occasionally more than once). If the time lag of re-entry into the small bowel is significant, the new landmark for entry into the duodenum should be marked. This is particularly so that the capsule reader correctly identifies the ampulla in the proximal small bowel and does not mistake it for a polyp.
In patients with suspected Crohn’s disease and negative ileocolonoscopy findings, the European Society of Gastrointestinal Endoscopy (ESGE) recommends small-bowel CE as the initial diagnostic modality for investigating the small bowel, in the absence of obstructive symptoms or known stenosis.2 However, 9-13% of healthy volunteers may have the presence of erosions on CE. Moreover, studies have shown that patients may have undeclared surreptitious use of nonsteroidal anti-inflammatory drugs (NSAID), which could be responsible for ulceration seen on CE.3,4 The findings on CE of NSAID enteropathy may be indistinguishable from that of Crohn’s disease.2 Patients with co-existing comorbidity who take drugs such as nicorandil may also have evidence of small bowel mucosal injury on CE. Therefore, a thorough history, including a detailed drug history, is pertinent prior to reporting CE and labelling findings as small bowel Crohn's disease, which may be a misdiagnosis.
Angioectasia are a common cause and finding in patients over the age of fifty years who present with obscure GI bleeding.5 Angioectasia in the small bowel are commonly located in the proximal small bowel and can be single or multiple with or without the presence of bleeding. The findings of angioectasia: number, size and stigmata of bleeding must be put in the context of the clinical presentation. If the findings are minor compared to the severity of the bleeding, it is imperative this is highlighted appropriately in the CE report to guide the referring clinician on further management, including looking for other potential sources of bleeding.
Reporting of submucosal bulges remains a challenging area for capsule endoscopists. Studies have shown that even the use of 3D imaging does not help experts, although it may improve the accuracy of novices.6 Parameters which can help to report include bleeding, mucosal disruption, vascular change and/or utilisation of the smooth protruding lesion index score on CE (Spice Score). The utilisation of this score gave a sensitivity and specificity of 83% and 89%, respectively, for the detection of small bowel tumours.7–9 Appropriate further management to verify CE findings, particularly in indeterminate cases, should include radiology and pursuing histology with device-assisted enteroscopy if clinically appropriate
CE is the first-line modality to investigate the small bowel in cases of obscure GI bleeding.2 The literature suggests the pickup rate is significantly higher in the older age group, patients who are transfusion dependent, and the closer the procedure is done to the presentation of bleeding.2 However, despite this, CE may be negative. It is important that clinicians recognise that CE does have a miss rate, particularly for small bowel tumours located in the proximal small bowel. If the clinical suspicion remains high, alternative modalities of investigation should be considered, or a repeat procedure should be advocated if the clinical presentation changes from occult to overt bleeding or a haemoglobin drop of > 4g/dL.10
A successful colon capsule examination needs a complete visualisation of the colon, starting from the cecum until the last rectal image within battery life. Colon capsule battery lifetime is, on average, more than 10 h. Several studies have a substantial incomplete procedure rate due to retrieval of the capsule system after 8h.11–13 If the colon capsule is not excreted in 8h, we suggest waiting until the battery ends.
A complete colon capsule procedure relies on the use of boosters to improve colonic transit times within battery life. ESGE colon capsule guidelines recommend boosters based on low-dose sodium phosphate if possible.14 When sodium phosphate is contraindicated, it should be replaced by other boosters with similar efficacy. Selection of the right booster is essential for capsule colonoscopy.
Retention is the most significant complication of CE, although it is still infrequent. Risk factors for retention include clinical suspicion of an obstruction, known strictures, history of abdominal radiation and previous abdominal surgery. However, those risk factors shouldn’t prevent from performing a capsule examination. To decrease the risk of capsule retention, a permeability test should be performed, preferably with the Agile Patency Capsule (Medtronic, Dublin). The Agile Patency capsule is a degradable capsule, the same size as the small bowel capsule, with a RIFD tag. This tag allows locating the capsule with a plain X-ray or CT scan. After 36h, the patency capsule starts to dissolve, so if the capsule has not been excreted before 30h, or it is excreted distorted, a small bowel stricture should be suspected, and the capsule procedure should be considered contraindicated.
In patients with suspected Crohn’s disease, the risk of retention is low. Hence, patency capsule shouldn’t be performed routinely unless patients have significant pain or obstructive features.15 In patients with known Crohn’s disease with no suspicion of strictures/ abdominal complaints suggesting small bowel obstruction, there’s no need to use a patency capsule.16
There is no need to check small bowel capsule excretion if the capsule recording shows the cecum, as the risk of capsule retention in the colon is very low. Considering the definition of capsule retention, the ESGE suggests confirmation of capsule location if the cecum has not been reached and the capsule has not been excreted within 15 days.15
At the beginning of the capsule era, implanted devices such as pacemakers were considered a contraindication for CE. Several studies have shown that there is no risk of dysfunction for neither the capsule nor the cardiac devices; ESGE recommends that patients with pacemakers or implantable cardioverter defibrillators (ICDs) and left ventricular assist devices (LVADs) can safely undergo small-bowel CE (SBCE) without special precautions.15
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About the Authors
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Your capsule endoscopy briefing
UEG online courses
UEG Week
- The effectiveness of an extended bowel preparation regimen in capsule endoscopy
- Nurse led Capsule endoscopy service
Standards & Guidelines
- Small-bowel capsule endoscopy and device-assisted enteroscopy for diagnosis and treatment of small-bowel disorders: European Society of Gastrointestinal Endoscopy (ESGE) Guideline – Update 2022
- Imaging alternatives to colonoscopy: CT colonography and colon capsule. European Society of Gastrointestinal Endoscopy (ESGE) and European Society of Gastrointestinal and Abdominal Radiology (ESGAR) Guideline – Update 2020
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