Scab vs. Eschar: Key Differences in Wound Healing
- mdavis107
- Oct 13, 2020
- 3 min read
Updated: Jun 2
In wound care, understanding the distinction between scabs and eschars is critical. Although the terms are sometimes used interchangeably, they describe very different clinical phenomena—and accurate terminology is essential for proper assessment, documentation, and treatment planning.
What Is a Crust (Formerly Called a Scab)?
Crust, commonly referred to in the past as a "scab," is composed of dried blood, serum, and other exudate that forms over superficial skin injuries. While the term “scab” is still widely used informally, wound care professionals have moved away from it in favor of “crust,” which is a more accurate and clinically accepted term.¹⁻¹⁰
Crust does not contain devitalized tissue and is not indicative of ischemia. It is a natural part of superficial wound healing and typically indicates a low-acuity process.
What Is Eschar?
Eschar refers to devitalized tissue—tissue that is dead or non-viable. It may present as soft or hard, wet or dry, and loosely or firmly adherent.¹⁻¹⁰ In wound care, eschar is often associated with underlying ischemia and can signal serious complications such as dry gangrene.
Originally, the term “eschar” was used in the context of burn injuries, but it now commonly describes necrotic tissue found in a variety of wound types, including diabetic foot ulcers and pressure injuries.
Why the Difference Matters
The distinction between crust and eschar is not just academic—it directly impacts clinical decisions, coding, and reimbursement.
Crust is composed of dried exudate. If removed and no wound is present underneath, debridement cannot be billed. In established patients, this typically reflects a healed outcome. For new patients, it often leads to discharge following consultation—if no other wounds are present.
Eschar, on the other hand, indicates devitalized tissue and must be evaluated carefully. It often results from poor perfusion and carries a risk of infection. Clinical guidelines recommend not debriding stable, dry eschars (also called dry gangrene) unless perfusion has been optimized. Debriding prematurely may increase infection risk and compromise tissue integrity.
SHS Clinical Reminder: When to Hold Off on Debridement
For wounds presenting with stable, dry, black eschar that is:
Non-tender
Non-fluctuant
Non-erythematous
Non-suppurative
…do not debride until perfusion status is determined. The eschar acts as a protective barrier against infection. If the eschar becomes soft, fluctuant, or shows signs of drainage, unroofing for culture and drainage may be appropriate.
"Do not debride stable, dry, black, non-tender, non-fluctuant, non-erythematous, and non-suppurative eschars until perfusion status is determined."
Collaborative clinical judgment is critical in these scenarios, particularly when balancing debridement risks with perfusion concerns.¹¹
References
Baranoski S. & Ayello EA. (2012). Wound care essentials: practice principles (3rd Ed.).
Bryant RA, & Nix DP. (2012). Acute & chronic wounds: current management concepts (4th Ed.).
Cohen IK, Diegelmann RF, & Lindbald WJ. (1992). Wound healing: biochemical & clinical aspects.
Davis JS, & Bales MG. (1999). Understanding wound healing and principles of wound management.
Goodheart HP. (2009). Goodheart’s photoguide to common skin disorders (3rd Ed.).
Kloth LC, & McCulloch JM. (2002). Wound healing: alternatives in management (3rd Ed.).
McCulloch JM, & Kloth LC. (2010). Wound Healing: evidence-based management (4th Ed.).
Myers BA. (2004). Wound management: principles and practice.
Shai A, & Maibach HI. (2005). Wound healing and ulcers of the skin: diagnosis and therapy.
Strauss MB, Aksenov IV, & Miller SS. (2010). Masterminding wounds.
Sussman C, & Bates-Jensen B. (2012). Wound care: a collaborative practice manual for health professionals (4th Ed.).
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