Pressure Ulcers are categorised into 4 stages of severity:
Grade 1 – reddened skin which persists for more than 30 minutes after pressure has been relieved.
Grade 2 – superficial skin damage. May present as a blister or as an abrasion.
Grade 3 – full thickness skin loss not extending to bone or muscle. This grade is not usually painful.
Grade 4 – full thickness skin loss with extensive tissue damage through muscle and bone.