by Keval Parikh and James McGuire DPM, PT, CPed, FAPWHc
by The WoundSource Editors
To witness the normal wound healing process is extraordinary. However, the systematic process of healing is not always perfect. Chronic wounds are complex and present an immense burden in health care. Identifying the wound etiology is important, but an accurate wound assessment is just as important. The color, consistency, and texture of wound tissue will lead you to the most appropriate wound management plan.
Wound Tissue Types
The process of epidermis regenerating over a partial-thickness wound surface or in scar tissue forming on a full-thickness wound is called epithelialization. The epithelium manifests as light pink with a shiny pearl appearance. Epithelial cells travel from the outward wound edges and crawl across the wound bed to wound closure. Once the epithelium is created, it becomes stronger in time.
Granulation tissue formation occurs in the proliferative phase. Healthy granulation is pink or red, with an uneven, mounded texture. These mounds are capillary loops or granulation buds. Dark, dusky granulation is a sign of ischemia, poor perfusion, and/or infection. The proliferative phase will reach completion when myofibroblasts help contract the wound and epithelial cells start resurfacing across the wound bed.
Healthy granulation tissue is pink or red and is a good indicator of healing. Unhealthy granulation is dark, dusky red, bleeds easily, and may indicate the presence of wound infection.
Excess granulation or "proud flesh" is called hypergranulation. The wound tissue will manifest above the normal wound bed surface.
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Slough is non-viable or devitalized tissue that can be fibrinous, adherent, stringy, or thickened. The color can vary from yellow, gray, green, brown, or tan. Slough harbors pathogenic organisms, increases the risk of infection, and impedes healing by keeping the wound in the inflammatory phase or state; therefore, debridement methods are warranted. Exposing viable tissue will expedite the healing progress.
Scab Versus Eschar
The term "eschar" is NOT interchangeable with "scab." Eschar is dead tissue found in a full-thickness wound. You may see eschar after a burn injury, gangrenous ulcer, fungal infection, necrotizing fasciitis, spotted fevers, and exposure to cutaneous anthrax. Current standard of care guidelines recommend that stable, intact (dry, adherent, intact without erythema or fluctuance) eschar on the heels should not be removed. Blood flow in the tissue under the eschar is poor, and the wound is susceptible to infection. The eschar acts as a natural barrier to infection by keeping the bacteria from entering the wound. If the eschar becomes unstable (wet, draining, loose, boggy, edematous, red), it should be debrided according to the clinic or facility protocol.1
The term "scab" is used when a crust has formed by coagulation of blood or exudate. Scabs are found on superficial or partial-thickness wounds. Scab is the rusty brown, dry crust that forms over any injured surface on skin within 24 hours of injury. Whenever our skin is injured as a result of any cut or abrasion, it starts bleeding secondary to blood flowing from the severed vessels. This blood—containing platelets, fibrin, and blood cells—soon clots to prevent further blood loss. The outer surface of this blood clot dries up (dehydrates) to form a rusty brown crust, called a scab, which covers the underlying healing tissues like a cap. The purpose of a scab is to prevent further dehydration of the healing skin underneath, to protect it from infections, and to prevent any entry of contaminants from the external environment. Scabs generally remain firmly in place until the skin underneath has been repaired and new skin cells have appeared, after which it naturally falls off.1
1. Carver C. Knowing the Difference Between Scab and Eschar. WoundSource.com. 2016. Available at: http://www.woundsource.com/blog/knowing-difference-between-scabs-and-eschar. Accessed April 15, 2018.
2. Liu WL, Jiang YL, Wang YQ, Li YX, Liu YX. Combined debridement in chronic wounds: a literature review. Chin Nurs Res. 2017;4(1):5–8. Available at: https://www.sciencedirect.com/science/article/pii/S2095771817300063. Accessed April 15, 2018.
3. Grey JE, Enoch S, Harding KG. ABC of Wound assessment. BMJ. 2006;332(7536):285–8. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1360405/. Accessed April 15, 2018.
The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.