A pressure sore is a lesion that develops on the skin and underlying tissues due to unrelieved pressure. The skin and tissues need enough blood supply for oxygen and nutrients. When tissues are compressed for an extended period from hours to days, blood supply can be cut off, leading to a sore.

Pressure Sore (Skin Ulceration)
Nucleus factsheet image
Copyright © Nucleus Medical Media, Inc.

Pressure sores result from lying or sitting in one position for too long a time. Prolonged pressure cuts off the blood supply to tissues that are compressed between a bony area and a mattress, chair, or other object. Without oxygen and nutrients, the tissue starts to die.

Several factors contribute to the development of pressure sores including:

  • Pressure—Pressure sores can result from the inability to change position or to feel discomfort caused by pressure. People with normal mobility and sensation change position automatically, without thinking.
  • Friction—Even friction from pulling someone across bed sheets can damage small blood vessels that supply the skin tissue.
  • Poor nutrition
  • Moisture—This can come from sweating due to fever or leakage of urine or stool.
  • Obesity —Extra weight increases pressure on the skin over the bones and joints.