In medicine, a<unk>  is a tube that is inserted into a natural conduit of the body to prevent or counteract a disease-induced localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow access for surgery.
Stent
Prosthesis
Colloid
Radiocontrast
Guidewire coatings
Allograft
Contrast 
Bandage