Systems, methods, and devices are disclosed that involve a fistula-isolatingdevice for use whenreduced pressure is applied to a wound bed having a fistula. In one instance,the fistula-isolatingdevice includes an adjustable passageway member and a perimeter member thatcontracts underreduced pressure and that automatically accommodates wound beds of differentheights. In anotherinstance, the fistula-isolating device involves a body shaped as a frustro-conical body that is readilysized for different depth wound beds. Other systems, methods, and devices arepresented.