The inability to visualize the ampulla of Vater is an inherent limitation of capsule endoscopy.

Objective: Lesions missed by capsule endoscopy (CE) have been reported and this may be partly because of the properties of the capsule. We aimed to compare the ability of Pillcam SB1, SB2, ESO1 and ESO2 to identify the ampulla of Vater (AoV).
Methods: Patients were divided into four groups: SB1 [single head capsule, 2 frames per second (fps), a 140° field of view, n=50], SB2 (single head, 2 fps, a wider field of view of 156°, n=50), ESO1 (double head, 14 fps, a 140° field of view, n=8) and ESO2 (double head, 18 fps, an extra wide field of view of 169°, n=12). Metoclopramide was administered in 25 out of 50 patients in SB1 group and all patients in SB2 group before CE.
Results: The AoV was not detected in any patients having SB1, irrespective of the use of metoclopramide. The AoV was identified in only nine out of 50 (18%) patients in the SB2 group confirming the benefit of a widened field of view, however, showed that even this capsule failed to visualize the AoV in more than three-quarters of cases. Double-headed capsules with faster frame rates did not improve the detection rate, the AoV was visualized in only one out of 12 (8%) patients in the ESO2 group but none in the ESO1 studies.
Conclusion: Currently, CE is not reliable to visualize the AoV and by inference the proximal duodenum. This is most likely related to the speed at which the capsule passes through the fixed second part of the duodenum. Faster frame rates plus a wider field of view do not overcome this limitation, which could account for missed lesions elsewhere in the small bowel.