A medical device according to the present invention is to be arranged in a lumen of a gastrointestinal tract. The medical device includes: at least one cylindrical part which is opened at at least one end thereof and at least one attachment part which is arranged on at least one portion of the cylindrical part and is configured such that the medical device is attachable to the lumen of the gastrointestinal tract. The cylindrical part is configured to be arrangeable along at least one portion of the gastrointestinal tract, and at least one portion of a side surface of the cylindrical part is configured to be followable to a shape of an inner wall of the gastrointestinal tract.
