a. Stage I Non-blanchable erythema of intact skin
b. Stage II partial-thickness skin loss involving the epidermis or dermis or both. The ulcer is superficial and manifests clinically as an abrasion, blister or shallow crater.
c. Stage III Full-thickness skin loss and damage or necrosis of subQ tissue that may extend to, but not through, underlying fascia. Deep crater.
d. Stage IV Full-thickness skin loss associated with extensive destruction, tissue necrosis, or damage to muscle, bone, or supporting structures such as tendons or joint capsules.