The present invention provides devices and methods for treating wounds. The devices may include polymer particles capable of absorbing fluid such as blood. When devices of the invention are exposed to fluid, the fluid may enter the device and cause the polymer particles to swell. Devices of the invention may also apply pressure on wound cavities to stop or restrict the flow of fluid. In some embodiments, the devices may comprise components to facilitate absorption of fluid throughout the device, such as wicking elements and/or multiple compartments. One or more of the devices can be placed directly in the wound cavity, or in a containment structure and then into the wound cavity.