Differential diagnosis of suspected deep tissue injury.

Deep tissue injury (DTI) can be difficult to diagnose because many other skin and wound problems can appear as purple skin or rapidly appearing eschar. The diagnosis of DTI begins with a thorough history to account for times of exposure to pressure, such as 'time down' at the scene or time during which the patient was flat and could not respond. Patients with light skin tones present with classic skin discolouration of purple or maroon tissue, a defined border around the area of injury, and often surrounding erythema is evident. Persistent erythema and hyperpigmentation, rather than blanching, should be used to determine pressure injury in dark skin tone patients. Differential diagnosis includes stage 2 pressure ulcers, incontinence-associated dermatitis, skin tears, bruising, haematoma, venous engorgement, arterial insufficiency, necrotising fasciitis and terminal skin ulcers. Many skin problems can also have a purple hue or rapidly developing eschar, and a working knowledge of dermatology is needed.