Use of the patency capsule in daily practice

 

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We read with great interest the article entitled “Use of patency capsule in patients with established Crohn’s disease” by Nemeth et al. [1]. Although some studies have evaluated the role of the patency capsule in patients with suspected small-bowel strictures [2] [3] [4], little is known regarding its use in daily practice. The study by Nemeth et al. included 406 video capsule ingestions in patients with established Crohn’s disease: 132 patients (32.5 %) underwent video capsule endoscopy without previous patency capsule test and 274 (67.5 %) received the patency capsule prior to capsule endoscopy. The patency capsule test was negative in 193 patients (70.4 %) and positive in 81 patients (29.6 %). A negative patency test did not eliminate the risk of capsule retention, as four patients (2.1 %) retained theirs, but the result was a very high negative predictive value (97.9 %). Conversely, a positive patency test resulted in video capsule retention in 11.1 % of performed cases (n = 18), and even the second-generation patency capsule resulted in a small-bowel obstruction in some cases (2.2 %). Nevertheless, as the present paper concludes, retained capsules could be resolved by nonsurgical methods.

We find these results very interesting, as this is the largest published series on the use of the patency capsule in “daily” practice. This paper also opens some old questions regarding patency capsule detection techniques. In general, it seems that the use of the patency capsule did not result in a significant decrease in the rate of video capsule retention. The rate of complications in those patients who did not undergo patency capsule was similar to that observed in patients who underwent patency capsule before video capsule endoscopy (2.3 % vs. 2.1 %). We wonder whether these results could be influenced by the technique selected for patency capsule detection (hand-held scanner or abdominal radiography). In fact, abdominal radiography is usually considered inaccurate for patency capsule location (small bowel vs. colon), and this may result in false-positive (i. e. patency capsule located at cecum or transverse colon) and false-negative (i. e. patency capsule located at pelvic ileum) results. However, there is a lack of scientific evidence to support the use of the hand-held scanner.

Would the authors consider location of the patency capsule in the colon to be a negative test? If so, the use of the hand-held scanner would result in some false-positive results as the capsule is still inside the patient. Conversely, do the authors think that the use of more accurate detection techniques such as low radiation dose computed tomography [5] could result in fewer false positives/negatives and thus more reasonable (i. e. significant) differences in video capsule retention rates? If so, what would the authors recommend for the future?

• References

• 1 Nemeth A, Kopylov U, Koulaouzidis A et al. Use of patency capsule in patients with established Crohn’s disease. Endoscopy 2015; DOI: 10.1055/s-0034-1393560.
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• 2 Boivin ML, Lochs H, Voderholzer WA. Does passage of a patency capsule indicate small-bowel patency? A prospective clinical trial. Endoscopy 2005; 37: 808-815
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• 3 Herrerias JM, Leighton JA, Costamagna G et al. Agile patency system eliminates risk of capsule retention in patients with known intestinal strictures who undergo capsule endoscopy. Gastrointest Endosc 2008; 67: 902-909
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• 4 Albuquerque A, Cardoso H, Marques M et al. Predictive factors of small bowel patency in Crohn’s disease patients. Rev Esp Enferm Dig 2015; DOI: 10.17235/reed.2015.3957/2015.
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• 5 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
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