System for wound treatment with serum, having a device for obtaining serum from whole blood, wherein the device comprises: - a blood bag for receiving whole blood and for coagulating the whole blood into a solid fraction containing the cell components of the blood and into a fluid containing serum, wherein the blood bag has an outlet for discharging the fluid from the blood bag and, in the region of the outlet, a gate which is suitable to retain at least a majority of the solid fraction, - a filter module having a fluid connection to the blood bag via the outlet of the blood bag, - wherein the filter module has a housing with an interior and an inner wall bordering the interior, in which is arranged a semipermeable membrane that subdivides the interior into a retentate space and a permeate space, - wherein the semipermeable membrane enables separation of the fluid discharged from the blood bag into a permeate, which comprises the serum, and a retentate in which particulate components that are possibly contained in the fluid remain, and - wherein the filter module has an inlet device for introducing the fluid discharged from the blood bag into the retentate space, a retentate outlet for discharging retentate from the retentate space, and a permeate outlet for discharging the permeate from the permeate space, and wherein the wound treatment system furthermore comprises a wound care system for outputting the permeate onto a wound, which wound care system has a first capillary membrane system in sheet form, wherein the first capillary membrane system is connected to at least one supply line such that fluids can be directed through the supply line and the first capillary membrane system and be supplied to a wound, and wherein the permeate outlet is connected to the first capillary membrane system via a permeate line comprising the at least one supply line of the first capillary membrane system. - a blood bag for receiving whole blood and for coagulating the whole blood into a solid fraction containing the cell components of the blood and into a fluid containing serum, wherein the blood bag has an outlet for discharging the fluid from the blood bag and, in the region of the outlet, a gate which is suitable to retain at least a majority of the solid fraction, - a filter module having a fluid connection to the blood bag via the outlet of the blood bag, - wherein the filter module has a housing with an interior and an inner wall bordering the interior, in which is arranged a semipermeable membrane that subdivides the interior into a retentate space and a permeate space, - wherein the semipermeable membrane enables separation of the fluid discharged from the blood bag into a permeate, which comprises the serum, and a retentate in which particulate components that are possibly contained in the fluid remain, and - wherein the filter module has an inlet device for introducing the fluid discharged from the blood bag into the retentate space, a retentate outlet for discharging retentate from the retentate space, and a permeate outlet for discharging the permeate from the permeate space, and - wherein the filter module has a housing with an interior and an inner wall bordering the interior, in which is arranged a semipermeable membrane that subdivides the interior into a retentate space and a permeate space, - wherein the semipermeable membrane enables separation of the fluid discharged from the blood bag into a permeate, which comprises the serum, and a retentate in which particulate components that are possibly contained in the fluid remain, and - wherein the filter module has an inlet device for introducing the fluid discharged from the blood bag into the retentate space, a retentate outlet for discharging retentate from the retentate space, and a permeate outlet for discharging the permeate from the permeate space, and