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Conventional optical colonoscopy is the reference examination for exploration of the colon. Its morbidity and its poor acceptability have led to the development of alternative techniques. Considerable work has gone into colon imaging, in particular computed tomography (colo-TC). According to the meta-analysis by Mulhall et al, its sensitivity is 85% and its specificity 97% for the detection of polyps9 mm. A colo-TC is the alternative examination with the best recognized performance. Among the examinations described below, it is the only examination that can be proposed in the case of the failure of or contraindication to optical colonoscopy. Because of the irradiating nature of this technique, magnetic resonance imaging would be preferable if feasible. This technique has appeared more recently, and work on the topic is less abundant. Capsule endoscopy (the Pill-cam) for the small intestine has been adapted to study of the colon. Results of colon capsule endoscopy studies are promising. A European multicenter study of 320 patients found a sensitivity of 64%, specificity of 84%, positive predictive value (PPV) of 60% and negative predictive value (NPV) of 86% for the detection of polyps6mm. No severe complication was observed. Finally, improvements have been sought for standard colonoscopy: the Aer-O-Scope, Invendoscope, CathCam colonoscopy - all of these alternative colonoscopies are only in their infancy. The characteristics of these methods for exploring the colon vary substantially between techniques, and their respective roles and indications remain to be defined.