Colon capsule for panendoscopy: a narrow window of opportunity

named M2A (M2A Capsule, GivenImaging Ltd, Yokneam, Israel) [1]. This acronym reveals the philosophy behind this technology: the implementation of a miniaturized system allowing to endoscopically evaluate the entire digestive system, ideally from the mouth to the anus (which is what M2A stands for). The technical barriers that had initially prevented the exploration of the entire surface of the digestive system have been removed over time through the development of batteries with longer life, the optimization of power consumption (e. g., through the adaptive frame rate) and the increase in the number of cameras and in the angle of view (to cover the entire mucosal surface of wider lumen organs). The study by Vuik et al. [2] in the current issue of Endoscopy International Open, as well as several other publications, [3] confirm that the endoscopic study of the entire surface of the digestive system appears to be now technically possible. However, does “technical feasible” also mean “clinically reliable”? Although the very quick small bowel transit time reported in the present study (median small bowel transit time: 47’) might negatively impact on small bowel capsule diagnostic yield, the key role of capsule endoscopy in the evaluation of the small bowel mucosa has been confirmed in several studies, and current guidelines endorse the use of this device as firstline examination in many clinical scenarios [4]. The clinical reliability concerns, therefore, are related mostly to the evaluation of the colonic, esophageal, and gastric mucosa, which would be the potential added value of panenteroscopy. In standard colonoscopy, there is a well-documented correlation between the degree of cleanliness and diagnostic performance [5]. This is likely to have even greater relevance in the field of wireless endoscopy, where the capsule is purely passive (e. g., it cannot wash or remove debris) and bowel preparation also plays a key role in promoting device propulsion. In the paper from Vuik et al. [2] the rate of patients with adequate colon cleansing (76.6%) was below the≥90% minimum standard recommended for optical colonoscopy [6], although involved subjects were healthy and highly compliant with the preparation schedule (93.6% of them took the entire bowel preparation). Although this may reflect the specific preparation schedule adopted in the study, a recent systematic review [3] showed that the rate of patients with adequate colon cleansing was highly variable, but ≥90% in only 54% of studies, even when different schedules were used. Furthermore, although no formal standard quality measure exists, the rate of patients with adequate cleansing of the whole gastrointestinal tract (52.8%) is far from being acceptable. Finally, as far as the completion rate for colon evaluation is concerned, the 51% rate reported by Vuik et al. [2] is similar to those reported in other publications [7–9] and far below the recommended threshold of 90% [6]. Although relevant gastric findings, missed by previous traditional gastroscopy, were reported in patients undergoing small bowel capsule endoscopy [10], the parameter for assessing the efficacy of panenteroscopy in evaluation of gastric mucosa (observation of more than 90% of the mucosa) appears to be arbitrary, contrived, and very difficult to measure. In the absence of a traditional examination as comparator, no clinically relevant conclusions can be drawn about the diagnostic yield in the stomach of such a non-steerable capsule. In addition, because Colon capsule for panendoscopy: a narrow window of opportunity