The invention relates to a stent for insertion into and placement inside a body cavity of a human being or an animal, said stent being intended for having a first configuration during insertion into the cavity and said stent, after having been placed in the cavity, being intended for having a second configuration. In an aspect of the invention, an expandable part is constituted by at least one first section of at least one helical winding in a clockwise direction and at least one second section of at least one helical winding in a counter-clockwise direction, each of said first and second at least one section being radially expandable so that during expansion, and where the at least one first section will be rotating in counter-clockwise direction and the at least one second section will be rotating in clockwise direction. In another aspect of the invention, a non-straight curvature of the retaining part is capable of conforming to a curvature of the body cavity, thereby avoiding migration of the stent along the body cavity, and substantially without application of radial forces from the retaining part onto the body cavity walls.
