Negative capsule endoscopy for obscure gastrointestinal bleeding is closely associated with the use of low-dose aspirin.

Objective. Capsule endoscopy (CE) is used widely for determining the cause of obscure gastrointestinal bleeding (OGIB). However, negative findings still arise from CE examination. The aim of this study was to determine the factors associated with negative findings on CE in patients with OGIB. Material and methods. A total of 134 patients who underwent CE for overt (n == 104) or occult (n == 30) OGIB between October 2007 and April 2010 were included. The clinical backgrounds of the patients (age; sex; the use of anti-coagulant, anti-platelet drugs or NSAIDs; comorbidity and the timing of CE examination after bleeding) were noted. Results. The overall diagnostic yield of CE in detecting the relevant findings was 50% (n == 67). Multivariate analysis revealed that the use of anti-platelet drug and the timing of CE (>= a parts per thousand yen16 days) were predictive factors for negative findings on CE (odds ratio 2.69 [1.01--7.21], p == 0.048 and odds ratio 2.32 [1.01--5.33], p == 0.047, respectively). Among the patients with the use of low-dose aspirin (LDA, n == 28) as anti-platelet drug, cessation of it before CE was the only predictive factor for negative findings on CE (odds ratio 12.0 [1.72--83.5], p == 0.012). Conclusion. In the patients with OGIB, the use of LDA and the cessation of it before CE made it difficult to detect the cause of bleeding by CE. This might indicate that the source of OGIB related to LDA heals immediately after cessation of the drugs or is a very small lesion that could not be detected by CE.