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Page 4 of 7 Bojórquez et al. Mini-invasive Surg 2023;7:8 https://dx.doi.org/10.20517/2574-1225.2022.65

CAPSULE RETENTION RISK
WHY? The use of capsule endoscopy in CD has expanded over the years for its capability of accurately
visualizing the entire SB, aiding in detection of disease activity, endoscopic recurrence, treatment response
and evaluation of mucosal healing through indexes .However, its use is hindered by the potential risk of
[23]
retention, which excludes high-risk patients from the benefits of SBCE. Radiological tests can also be used to
exclude stenosis, which would deter SBCE. Both patency capsules and cross-sectional imaging have similar
[2]
high negative predictive values . Unlike patency capsules, MRE evaluation does not depend on intestinal
motility, eliminating potential false-positive results but overestimating the risk of retention as it has a high
sensitivity but a low specificity of around 60% . Therefore, if SB patency was evaluated only by MRE, fewer
[1]
SBCE procedures would be performed due to MRE’s overestimation of true stenosis .
[24]
WHEN? Capsule retention occurs when the capsule remains in the gastrointestinal tract within two weeks
after ingestion. Retention is mostly asymptomatic, and the capsule is naturally excreted after two weeks in
about 30% of patients Capsule retention can occur in any SB condition, not limited to CD. A high risk of
retention has been associated with small bowel tumors, anastomoses, radiation and NSAID enteropathy. In
these scenarios, capsule ingestion may result in perforation or acute obstruction requiring endoscopic
retrieval or surgical intervention .
[23]

In established CD, reported retention rates are high, ranging from 2% to 13% [2,25] ; Nemeth et al. designed a
multicenter retrospective study of 406 patients with established CD to evaluate the appropriate utilization
strategy of the patency capsule to reduce the risk of capsule retention. The authors compared a selective
strategy, which was the use of the patency capsule in patients with high-risk features, with a non-selective
strategy, the use of patency capsule in all patients with established CD. The study results concluded that
both utilization strategies had similar risk retention (1.3% vs. 1.6%, P = n.s), but with a selective strategy,
[24]
more capsules were performed, leading to an improved diagnostic yield and reduced costs .

In suspected CD without obstructive symptoms, known stenosis or history of small bowel resection, the rate
of capsule retention is approximately 1.5% , similar to patients with obscure gastrointestinal bleeding.
[5]
Therefore, it is not compulsory to evaluate small bowel patency prior to SBCE .
[24]
A recent metanalysis was performed to evaluate retention rates in the adult and pediatric CD, 3.49% in
adults and 1.64% in children. The retention risk in adult established CD was 3.4 times higher than in
suspected CD. When small bowel patency was evaluated, the retention rate of established CD was reduced
[23]
to 2.8% . The retention rates are significantly lower in studies that systematically performed cross-sectional
imaging or patency capsules before SBCE. If retention occurs, medical treatment for CD should be started
or maintained to allow for spontaneous passing. Depending on the symptoms and localization, one should
decide on endoscopic retrieval or surgical consultation [5,26] .

HOW? A patency capsule can be used to confirm intestinal patency, especially if small bowel stenosis is
suspected and has not been firmly excluded. A patency capsule indicates a safe SBCE exploration can be
done when the passage to the colon of an intact patency capsule has been radiologically confirmed, when it
[5]
is excreted before 30 h or excreted after 30 h but intact .

USE OF PAN-ENTERIC CAPSULE IN CROHN’S DISEASE
Considering the mouth to anus distribution of CD, it would be reasonable to use a study that allows
inspection of the entire digestive tract. Exploring this idea, Leighton et al. conducted a feasibility study of
the pan-enteric capsule (PEC) (PillCam CROHN’S, Medtronic, Yoqneam, Israel) comparing its diagnostic