Hematoma-related necrosis of flaps does not occur solely because of the “internal pressure” generated. A toxic effect of a mass of blood on skin flaps has been demonstrated in an experimental rat model, and this phenomenon in independent of the level of bacterial contamination. a high molecular weight constituent of the hemolysate also causes necrosis of an overlying flap.
The salvage of flaps overlying hemotomas can be improved by evacuation of the underlying blood before 12 hours. Also, a “delay” procedure done one week beforehand protects a flap from the distal tissue necrosis which occurs over a hematoma of moderate size.