Patent ID: 7182788

Claim:
A stent comprising: a cylindrical main body contractible and expandable in a circumferential direction; a cover member coated on an inner and/or outer circumference of the main body; and inverse current preventing means for preventing food or fluid from reversely flowing, the inverse current preventing means being disposed in the main body, wherein the inverse current preventing means comprises: a generally cylindrical fixing layer having an outer circumferential surface and an inner surface, the inner surface defining a passage having a diameter capable of allowing food and fluid to pass, the fixing layer being fixed in the main body by adhering the outer circumferential surface of the fixing layer to the inner circumference of the main body; and a valve layer extending from the fixing layer toward a distal end of the main body, the valve layer comprising an elongate passage formed of a flexible material and extending toward the distal end of the main body, the elongate passage having an opened configuration and a collapsed configuration, the elongate passage comprising: at least two creases in the flexible material, the creases extending along the passage generally parallel to the central axis of the main body, wherein the at least two creases are configured to resiliently bias the elongate passage toward the collapsed configuration.