A wound closure apparatus having a porous pad adapted to be fluidly connected to a vacuum pump. The pad is placed over or within a tissue site, and the vacuum pump may be activated to draw air and exudates from the tissue site. The pad contains multiple pore sizes to prevent granulation tissue from migrating into the pad as reduced pressure treatment is applied. The pad has an outer surface adjacent the wound with pore sizes of a diameter of approximately 100 microns or less to prevent tissue from growing into the pad and is treated for biocompatibility.