Abstract
Endoscopy of the total colon has made much progress after repeated improvements of the colonoscope and technique of insertion, however, there still remain some difficulties. In our department, colonoscopy is performed without fluoroscopic controle in all cases. How-ever, at the sigmoid-descending junction or other strongly bending portion, it sometimes takes time in finding the bowel lumen. Furtheremore, the lesions behind the semilunal folds or just inner side of strongly bending portions may be overlooked occasionally. To resolve these difficulties, the authors emphasized the usefulness of the colonoscope with a wider view field since the beginning of its development. Now, for practical use, the authours have made a trial model colonoscope with a wider view field in cooperations with Olympus Optical Co.. Clinical significance of such wider view field has been studied, the results of which are stated below. Advantages of the colonoscope with a wider view field: (1) The bowel lumen can be found more easily, which makes it easy to introduce the instrument into the proximal colon. (2) A wider area of lesions including stenosis can be easily observed. (3) It is superior in observation of such areas as behind the semilunar folds or just inner side of strongly bending portions, which tend to be blind area. Disadvantage with a wider view field : (1) Distortion of the image is much larger than that of the conventional one.But in practical use, there seems to be little problem as to the distortion of the image with the examiner becoming experienced in using the wide angle lens. In conclusion, a colonoscope with a wider view field seems to have more advantages as a whole in comparison with the conventional instrument.
