An open-cavity, reduced-pressure treatment device and system for treating a cavity in a patient's body, such as an abdominal cavity, is presented. In one instance, an open-cavity, reduced-pressure treatment device includes a plurality of encapsulated leg members, each having an interior portion with a leg manifold member and formed with fenestrations operable to allow fluid flow into the interior portion, and a central connection member fluidly coupled to the plurality of encapsulated leg members. The central connection member has a connection manifold member. The open-cavity, reduced-pressure treatment devices, systems, and methods allow for, among other things, removal of fluids.