The four stages of pressure ulcers from least severe to the most are: stage 1 or nonblanchable erythema, stage 2 or partial thickness, stage 3 or full-thickness skin loss, and stage 4 or full-thickness tissue loss, according to the National Pressure Ulcer Advisory Panel. There are two additional stages for pressure sores that cannot be classified, including full-thickness skin or tissue loss at an unknown depth and possible deep tissue injuries at an unknown depth.
In a stage 1 pressure sore, the skin is still intact, but it may appear red or discolored over a contained area of the body, especially over a bony area, explains the National Pressure Ulcer Advisory Panel. Pain in the area and skin that is firm, soft, warmer or cooler compared to surrounding skin are common symptoms of stage 1 pressure sores.
A stage 2 pressure ulcer indicates a break in the topmost layer of skin, according to Model Systems Knowledge Translation Center. A break may also appear in the second layer of skin. Symptoms include drainage or fluid leakage present in the area of the sore.
In stage 3, the pressure sore extends below the second layer of skin and into the fat, states Model Systems Knowledge Translation Center. However, no bone, muscle or tendon is visible through the wound. A stage 4 pressure ulcer extends below the fat into the muscle and can possibly extend all the way to the bone.