The principle of indigo carmine

The surface of normal digestive tract mucosa is smooth, but when there are minor lesions, such as ulcers and canceration. The surface will change, but in the early days, it is difficult to find it under ordinary endoscopy because the change is very small. The principle of contrast in the use of dyes. When the dye is sprayed on the mucosa, indigo carmine can not be deposited on the smooth surface, but all of it is deposited between the furrows of the mucosal folds, which is in sharp contrast with the orange mucosa. Under direct vision, a continuous line is formed to show the subtle concave-convex changes of mucosa and its three-dimensional structure, which is conducive to the early detection of inconspicuous tumors and other diseases in clinic and provides conditions for early detection and treatment of patients. It is a physical action to express the microstructure by using the color difference after dye deposition, and there is no chemical reaction. It is not observed by staining the tissue, and it does not interact with the mucosal tissue itself. Pigment is deposited in mucosal folds, not absorbed, not combined with mucus, and excreted through the intestine.