Eschar vs Slough

What Is Eschar? 

Eschar is a form of necrotic tissue that appears as dry, thick, leathery tissue that is usually black or dark brown. It may also appear tan in some cases. Eschar forms when tissue undergoes prolonged ischemia, resulting in full-thickness tissue death. It is commonly seen in pressure injuries, arterial ulcers, burns, and severe traumatic wounds. 

Eschar is typically firm or hard to the touch and may be adhered tightly to the wound bed. Because it represents devitalized tissue, it can impede wound healing by acting as a physical barrier to granulation tissue formation. However, not all eschar should be removed. For example, stable, dry eschar on the heel of a patient with poor arterial perfusion may serve as a natural biologic cover and should not be debrided unless signs of infection or instability are present. 

Understanding the context of the wound is essential before determining management. 

What Is Slough? 

Slough is also nonviable tissue, but it differs from eschar in both appearance and composition. Slough typically presents as moist, soft, and stringy tissue that may be yellow, tan, gray, or green. It consists of fibrin, cellular debris, bacteria, and inflammatory exudate. 

Unlike eschar, slough is usually loosely attached to the wound bed, although it can adhere in some areas. It often accumulates in wounds with moderate to heavy exudate and is common in venous leg ulcers, pressure injuries, diabetic foot ulcers, and infected wounds. 

Slough delays healing by maintaining a pro-inflammatory environment and serving as a medium for bacterial growth. In most cases, removal of slough through appropriate debridement supports progression to granulation and epithelialization. 

Eschar vs Slough: Key Differences in Appearance and Texture 

Distinguishing eschar from slough begins with careful visual and tactile assessment. 

Eschar is generally dry, thick, and dark in color. It often feels hard or leathery and may be firmly attached to the wound margins and base. The surface may appear cracked or scab-like. 

Slough, in contrast, is moist and soft. It may appear stringy or mucinous and can shift slightly when irrigated. Its color ranges from pale yellow to gray or green, depending on the level of exudate and bacterial presence. 

Lighting, wound cleansing, and gentle probing can help clarify tissue type. Because color alone is not sufficient for identification, wound care nurses must assess texture, moisture level, and adherence in addition to visual characteristics. 

Causes of Eschar and Slough in Wounds 

Both eschar and slough result from tissue death, but the mechanisms often differ. 

Eschar typically forms due to severe ischemia or full-thickness tissue injury. Prolonged pressure, arterial insufficiency, burns, and trauma can all compromise blood flow to the point of complete tissue necrosis. In these cases, desiccation of the devitalized tissue contributes to the dry, hardened appearance. 

Slough forms as part of the inflammatory response to tissue injury. When cells die and break down in a moist wound environment, they combine with fibrin and exudate to create soft necrotic material. Slough is often associated with chronic inflammation, high bioburden, and impaired drainage. 

Recognizing the underlying cause of necrosis informs both treatment and prognosis. 

Clinical Implications: Why Accurate Identification Matters 

Misidentifying eschar as slough, or vice versa, can lead to inappropriate treatment decisions. For example, aggressively debriding stable heel eschar in a patient with poor arterial flow can expose deeper structures and increase infection risk. Conversely, failing to remove slough may prolong inflammation and delay healing. 

Accurate tissue identification also affects wound staging. In pressure injuries, the presence of obscuring necrotic tissue may result in classification as an unstageable pressure injury until sufficient debridement allows visualization of the wound base. 

For wound care nurses, thorough assessment and interdisciplinary communication are essential to ensure appropriate care planning. 

Debridement Considerations for Eschar vs Slough 

Debridement is often indicated for slough. Methods may include autolytic, enzymatic, mechanical, conservative sharp, or surgical debridement depending on the wound characteristics and patient factors. Removal of slough reduces bacterial burden and supports progression to healthy granulation tissue. 

Eschar management requires greater caution. Stable, dry eschar without erythema, drainage, fluctuance, or signs of infection may be left intact, particularly on ischemic heels. However, eschar that becomes soft, boggy, draining, or associated with cellulitis may require urgent intervention. 

Before performing any debridement, wound care nurses must assess vascular status. An ankle-brachial index or other vascular studies may be necessary to ensure adequate perfusion for healing. 

Assessment and Documentation Best Practices 

Accurate documentation should describe tissue type, color, consistency, percentage of wound bed involvement, odor, drainage, and surrounding skin condition. Rather than documenting only “necrotic tissue,” clinicians should specify whether eschar, slough, or a combination is present. 

Clear terminology supports appropriate coding, staging, and interdisciplinary understanding. Photographic documentation, when permitted by policy, can also enhance continuity of care. 

Regular reassessment is critical, as wound tissue characteristics can change over time with treatment or clinical decline. 

Infection Risk and Complications 

Both eschar and slough can harbor bacteria. Slough, in particular, provides a moist environment conducive to microbial growth. Signs of infection may include increased exudate, malodor, periwound erythema, warmth, pain, or systemic symptoms. 

Dry, intact eschar may serve as a temporary barrier against infection. However, once it becomes unstable or begins to separate, the risk of underlying infection increases. 

Wound care nurses should monitor closely for changes in tissue stability, drainage patterns, and patient symptoms. 

What Wound Care Nurses Need to Know About Eschar vs Slough 

Strong assessment skills are foundational to differentiating eschar from slough. Visual inspection alone is not enough. Texture, moisture level, adherence, wound etiology, and perfusion status must all be considered. 

Treatment decisions should be individualized. While slough generally requires removal to promote healing, eschar may either need cautious debridement or protection, depending on the clinical context. Vascular assessment is especially important before intervening in ischemic wounds. 

Education is also key. Patients and caregivers may mistake eschar for a simple scab or may not understand why some necrotic tissue is removed while other areas are left intact. Clear explanations help support adherence and reduce anxiety. 

How to Measure Wound Depth with Slough and Eschar in the Way 

Measuring wound depth becomes more complex when slough or eschar obscures the wound bed. Accurate depth assessment is essential for staging, treatment planning, and monitoring progress, but nonviable tissue can prevent full visualization of underlying structures. 

When slough or eschar covers the base of a wound and prevents visualization of the true depth, the wound should be documented as unstageable if it is a pressure injury. Depth cannot be accurately determined until enough nonviable tissue is removed to expose the wound base. Attempting to “estimate” depth beneath firmly adherent eschar can lead to inaccurate staging and inappropriate treatment decisions. 

If slough is loosely attached and safe to remove, appropriate debridement may allow for accurate measurement. After sufficient cleansing or debridement, depth should be measured using a sterile, single-use cotton-tipped applicator. The applicator is gently inserted into the deepest visible portion of the wound bed without forcing it through adherent necrotic tissue. The applicator is then held level with the wound margin and measured against a ruler in centimeters. 

When stable, dry eschar is present and not appropriate for debridement, such as on an ischemic heel, the wound depth should not be probed through the eschar. Instead, documentation should reflect that the wound base is obscured by stable eschar and that depth cannot be determined at this time. For example: “Wound bed covered by 100% dry, stable black eschar. Depth unable to be assessed due to nonviable tissue.” 

In wounds where partial slough is present but portions of the wound bed are visible, depth measurement should be taken only in visible, viable areas. Documentation should also include the percentage of the wound bed covered by slough or eschar, as this affects both staging and treatment planning. 

Undermining and tunneling require special consideration. If necrotic tissue prevents safe exploration, forcing a probe can cause tissue damage or introduce bacteria. Assessment should be gentle and performed only when clinically appropriate. 

For wound care nurses, the priority is accuracy and safety. If the wound base cannot be visualized, it cannot be staged or measured definitively. Clear documentation protects the clinician, supports regulatory compliance, and ensures continuity of care until appropriate debridement allows full assessment.