Stages of pressure sores

Pressure sores (bed sores) are an injury to the skin and underlying tissue. They can range from mild reddening of the skin to severe tissue damage—and sometimes infection—that extends into muscle and bone. Pressure sores are described in four stages:

• Stage 1 sores are not open wounds. The skin is closed and may be painful. The skin may appear reddened but there are no breaks or tears in the skin. Skin temperature is often warmer. And the stage 1 sore can feel either firmer or softer than the area around it.
• At stage 2, the skin breaks open, wears away, or forms an ulcer, which is usually tender and painful. The sore expands into deeper layers of the skin. It can look like a scrape (abrasion), blister, or a shallow crater in the skin. Sometimes this stage looks like a blister filled with clear fluid. At this stage, some skin may be damaged beyond repair or may die.
• During stage 3, the sore gets worse and extends into the tissue beneath the skin, forming a small crater. Fat may show in the sore, but not muscle, tendon, or bone.
• At stage 4, the pressure sore is very deep, reaching into muscle and bone and causing extensive damage. Damage to deeper tissues, tendons, and joints may occur.

In stages 3 and 4 there may be little or no pain due to significant tissue damage. Serious complications, such as infection of the bone (osteomyelitis) or blood (sepsis), can occur if pressure sores progress.

Sometimes a pressure sore does not fit into one of these stages.

• In some cases, a deep pressure sore is suspected, but cannot be confirmed. When there isn't an open wound but the tissues beneath the surface have been damaged, the sore is called a deep tissue injury (DTI). The area of skin may look purple or dark red, or have a blood-filled blister. If you or your doctor suspect a pressure sore, the area is treated as though a pressure sore has formed.
• There are also pressure sores that are "unstageable," meaning that the stage is not clear. In these cases, the base of the sore is covered by a thick layer of other tissue and pus that may be yellow, gray, green, brown, or black. The doctor cannot see the base of the sore to determine the stage.