The key difference between scab and eschar is that scab is composed of dried blood and exudates normally found in superficial or partial-thickness wounds, while eschar is composed of necrotic tissue normally found in full-thickness wounds.
Wound healing is a complex process of four distinct phases: inflammation, destruction, proliferation, and maturation. Sometimes, wound healing is known as a healing cascade. The inflammatory phase prevents further blood loss by vasoconstriction. The destructive phase prevents infection, cleans the wound, and provides the best condition for healing. During the proliferation phase, the former structure is restored. The maturation phase is a redecorating phase that reduces the size of the wound.
CONTENTS
1. Overview and Key Difference
2. What is Scab
3. What is Eschar
4. Similarities – Scab and Eschar
5. Scab vs Eschar in Tabular Form
6. Summary – Scab vs Eschar
What is Scab?
Scab is crust made up of dried blood and exudates. It is normally found in superficial or partial thickness wounds. Scab is the rusty brown, dry crust that forms over a wound or any injured surface on the skin. It forms within 24 hours of the injury. Whenever the skin is injured due to any cut or abrasion, the wound starts bleeding due to the blood flowing from severed blood vessels. This blood normally contains platelets, fibrin, and blood cells. Soon, this blood forms clots to prevent further blood loss. Later, the outer surface of the blood clot dries up or dehydrates. This forms a rusty brown crust called a scab. The scab covers the underlying healing tissue like a cap.
Figure 01: Scab
The purpose of the formation of a scab is preventing further dehydration of the healing skin underneath, protecting it from infections, and preventing any entry of contaminants from the external environment. Until the skin underneath has been repaired and new skin cells have appeared, the scab remains firmly in place. After that, the scab will naturally fall off.
What is Eschar?
Eschar is composed of necrotic tissue that is normally found in full-thickness wounds. Eschar generates after a burn injury, gangrenous ulcer, fungal infection, necrotizing fasciitis, spotted fever, and exposure to cutaneous anthrax. Eschar is sometimes known as a black wound because the wound is covered with thick, dry black dead tissue.
Figure 02: Eschar
Eschar is dryer than slough and adheres to the wound bed. Furthermore, it has a spongy or leather-like appearance. The blood flow in the tissue under the eschar is poor, and the wound is susceptible to infection. However, eschar acts as a natural barrier to infection. It keeps away bacteria from entering the wound. Eschar may be allowed to slough off naturally. In case if the eschar becomes unstable, it should be debrided according to standard protocol.
What are the Similarities Between Scab and Eschar?
- Scab and eschar are two tissue types that generate during wound healing.
- Both tissue types are generated on the wound bed.
- They are a natural barrier to infections.
- They keep away bacteria from entering the wound.
What is the Difference Between Scab and Eschar?
Scab is composed of dried blood and exudates, which are normally found in superficial or partial-thickness wounds, while eschar is composed of necrotic tissue, which is normally found in full-thickness wounds. Thus, this is the key difference between scab and eschar. Furthermore, scab forms in the inflammatory phase of wound healing, while eschar forms in the destruction phase of wound healing.
The below infographic presents the differences between scab and eschar in tabular form for side by side comparison.
Summary – Scab vs Eschar
Scab and eschar form in the wound bed during wound healing. Scab is composed of dried blood and exudates that are normally found in superficial or partial-thickness wounds, while eschar is composed of necrotic tissue that is normally found in full-thickness wounds. So, this summarizes the difference between scab and eschar.
Reference:
1. Kristen Gasnick, PT. “Scabs: Why They Itch and How They Heal.” Verywell Health, Verywell Health, 29 Nov. 2021.
2. Nall, Rachel. “What You Need to Know about Eschar.” Healthline, Healthline Media, 13 Dec. 2019.
Image Courtesy:
1. “Knee scab and bruise” By Steven Vance (CC BY-NC-SA 2.0) via Flickr
2. “Scrub typhus eschar” By Paula Santibáñez, Ana M. Palomar, Aránzazu Portillo, Sonia Santibáñez andJosé A. Oteo – The Role of Chiggers as Human Pathogens. In: An Overview of Tropical Diseases. InTech Open (2015), pp. 173-202. https://dx.doi.org/10.5772/61978 (CC BY-SA 3.0) via Commons Wikimedia