Bedsore Injury Stages

Identifying the stage of a pressure ulcer is essential to developing a treatment plan. There are four defined stages of bedsores, which are organized by depth, severity and other characteristics.

Bedsores may cause tenderness, warmth, redness, swelling and other side effects. The degree of damage may range from irritated, unbroken skin to a deep injury affecting muscle, tissue and bone.

Stage I Pressure Sores

Non-blanchable erythema is the mildest stage, affecting only the upper layer of the skin.

The skin is still intact, with non-blanchable redness located over a bony area. Changes in sensation, temperature, or firmness may precede visual changes.If the spot doesn’t get lighter when you press on it, or even 10 to 30 minutes after you stop pressing, that indicates a restriction of blood flow. It may be harder to diagnose in people with darker skin.


  • Pain, burning, itching
  • Firm, soft, warm, cooler spots
  • Redness and discoloration

Stage II Pressure Sores

Partial-thickness skin loss with exposed dermis.

Skin loss is presenting as a shallow, open ulcer with a red pink wound bed. It may appear intact, or rupture as a pus-filled blister. It will look shiny or dry. Fat and deep tissue is not visible. This stage doesn’t describe moisture associated skin damage (MASD) including incontinence associated dermatitis (IAD), intertriginous dermatitis (ITD), medical adhesive-related skin injury (MARSI), or traumatic wounds (skin tears, burns, abrasions).


  • Pain
  • Swollen, warm, red
  • Broken skin, open wounds
  • Oozing clear fluid or pus

Stage III Pressure Sores

Full thickness tissue loss with potentially visible subcutaneous fat.

Bone, tendon or muscle are not exposed. The bridge of the nose, ear, occiput and malleolus do not have (adipose) subcutaneous tissue and Category/Stage III ulcers can be shallow.


  • Looks like a crater
  • Bad odor
  • Red edges, pus, odor, heat, and/or drainage

Stage IV Pressure Sores

Full thickness tissue loss with exposed bone, tendon or muscle.

The depth of stage IV pressure ulcers vary by location. The bridge of the nose, ear, occiput and malleolus do not have (adipose) subcutaneous tissue and these ulcers can be shallow. Category/Stage IV ulcers can extend into muscle and/or supporting structures (e.g., fascia, tendon or joint capsule) making osteomyelitis or osteitis likely to occur.


  • Deep, large sore
  • Black skin
  • Signs of infection, including red edges, pus, odor, heat, and/or drainage
  • Visible tendons, muscles, and bone

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