Use of patency capsules in patients with established Crohn’s disease

We read with interest the article by Nemeth et al. regarding the use of patency capsules in patients with established Crohn’s disease [1]. Two strategies of patency capsule use were evaluated: selective (used only in patients with a high risk of retention) and nonselective (used in all patients with Crohn’s disease). The authors concluded that video capsule retention in patients with established Crohn’s disease was relatively rare, and that nonselective use of a patency capsule did not reduce the risk of video capsule retention.

The use of patency capsules in patients with Crohn’s disease varies across centers and, to date, no guidelines for their use have been developed. In the Nemeth study, 88.9 % of the positive patency capsule tests were confirmed by a hand-held scanner. However, the hand-held scanner could only confirm whether or not the patency capsule remained within the body. Thus, a certain proportion of patency capsules that were retained in the colon were recorded as positive tests, resulting in patients being precluded from undergoing video capsule endoscopy (VCE). Plain abdominal radiography and computed tomography (CT) can be used to locate the patency capsule within either the colon or the small bowel. However, plain abdominal radiography has been demonstrated to be inaccurate in localizing the patency capsule and CT involves radiation exposure. A recent study demonstrated the benefit of a minimal radiation method of limited CT in confirming the location of the patency capsule [2].

Even after a negative patency capsule test, video capsule retention may still occur in clinical practice. In the Nemeth study, the patency capsule test was negative in 193 patients, four of whom subsequently experienced capsule retention during VCE. The interval between VCE and the patency capsule test may explain the false-negative results [3]. If the interval between patency capsule test and VCE is too long, the patency of the small bowel may change [4], especially in patients with Crohn’s disease. It is better to shorten the interval between the patency capsule test and VCE in order to reduce the number of false-negative patency results. A recent study showed that none of the 87 patients with a negative patency capsule test experienced video capsule retention during VCE performed within a week [4].

Small-bowel strictures or stenosis, and anastomosis may be radiologic predictors of capsule retention [4] [5]. It seems that patients with established Crohn’s disease with small-bowel strictures and a history of surgical anastomosis are more likely to be at risk of capsule retention. Considering the low retention rates in the two strategies in the Nemeth study, we believe that a large and prospective study is needed to confirm whether patency capsules should be administered in all patients with established Crohn’s disease.

We agree with the authors that for patients with Crohn’s disease and a positive patency capsule test, VCE should be viewed with caution. But we also believe that it is better to shorten the interval between patency testing and VCE in order to reduce the risk of video capsule retention.

• References

• 1 Nemeth A, Kopylov U, Koulaouzidis A et al. Use of patency capsule in patients with established Crohn’s disease. Endoscopy 2016; 48: 373-379
• 2 Assadsangabi A, Blakeborough A, Drew K et al. Small bowel patency assessment using the patency device and a novel targeted (limited radiation) computed tomography based protocol. J Gastroenterol Hepatol 2015; 30: 984-989
• 3 Yadav A, Heigh RI, Hara AK et al. Performance of the patency capsule compared with nonenteroclysis radiologic examinations in patients with known or suspected intestinal strictures. Gastrointest Endosc 2011; 74: 834-839
• 4 Nakamura M, Hirooka Y, Yamamura T et al. Clinical usefulness of novel tag-less Agile patency capsule prior to capsule endoscopy for patients with suspected small bowel stenosis. Dig Endosc 2015; 27: 61-66
• 5 Al-Bawardy B, Locke G, Huprich JE et al. Retained capsule endoscopy in a large tertiary care academic practice and radiologic predictors of retention. Inflamm Bowel Dis 2015; 21: 2158-2164