Think You Know Slough Wounds?

As a wound care provider, you understand that many things can affect the wound healing process, which is what makes chronic wound management so difficult. You also know that failing to pinpoint the root cause doesn’t just stall wound healing; it can lead to overall worsened health outcomes.

While there’s no exact numbers to confirm how often systemic factors are the reason for non-healing wounds, it’s still a widely accepted belief among professionals that they’re a primary culprit. However, this pervasive focus can inadvertently lead to the oversight of critical local factors, such as the presence of slough, which may be directly impeding recovery. 

To shed light on this often oversimplified factor, we’re going to discuss what slough wounds are, how they impact the wound healing process, ways to treat them, and more.

What Are Slough Wounds? 

First, let’s clarify that the term “slough wound” isn’t an actual diagnosis; instead, it’s an informal phrase people use to describe wounds with slough. Individuals must understand this nuance in wound care terminology to ensure it’s not mistakenly classified in the same manner as a “pressure wound” or “diabetic wound”. 

If you’re not careful, use of the shorthand phrase “slough wounds” could lead to some misconceptions, especially among healthcare providers who don’t specialize in wound care. For instance, if it’s documented in the electronic health record that “patient B has a slough wound”, it doesn’t provide any indication of why the wound exists. This lack of specificity doesn’t communicate to others if the patient has a venous ulcer, abrasion, or some other type of wound. And without this knowledge, it’s difficult to determine how to manage the wound. 

The phrasing, “wound with slough,” is more appropriate, as it tells you that the wound has slough in it. This better separates the wound’s etiology from its current state. 

So, What Is Slough in Wounds? 

As we mentioned, slough is a feature or component that sometimes appears in a wound and therefore isn’t a type of wound itself. Research describes it as “devitalized tissue that overlays the wound bed.” 

Its presence signals that something is hindering the body’s natural debridement mechanisms, which, in normal conditions, efficiently clear debris. For example, white blood cells might help break down and consume dead cells, and blood flow could aid in carrying waste products away. Yet, when these actions aren’t happening, it’s a sign that you’re dealing with a wound that isn’t healing properly, and can be or become a chronic wound. In fact, the presence of slough is a hallmark feature of chronic wounds and thus requires appropriate clinical action. 

The Characteristics of Slough Wounds

You’ll find that slough’s appearance varies largely, differing from wound to wound and patient to patient. This article highlights that slough properties, including how thick or thin it is, its smell, and how tightly it sticks to the wound bed, can vary considerably, even from one spot to another within the same wound. 

Yet, while it fluctuates, there are some common characteristics practitioners can look for, including: 

• Odor. Slough may have an unpleasant odor if infected or highly colonized with bacteria. 
• Color. Typically, it appears yellow or tan, though an infection can cause it to look off-white, grayish, or even greenish. 
• Texture. This might be fibrous, soft, and stringy with a high viscosity.  
• Hydration status. Slough is often observed as moist or wet, though, it can actually also be dry. 
• Location. It sits on top of the healthier tissue in the wound bed; slough might appear either in isolated patches or spread over the whole wound.  
• Adherence. Slough may be loosely attached and simple to remove, or it can be stubbornly adhered to the wound bed, necessitating aggressive debridement.  

What Is the Biological Composition of Slough Wounds? 

To effectively manage slough, it’s crucial to delve into the biological mechanisms underlying its formation and its intricate molecular and cellular composition. Therefore, let’s discuss the biological make-up of slough wounds to better understand how to manage them. 

First, let’s establish that necrotic tissue, or non-viable tissue, is a result of necrosis, which is the process of cell and tissue death due to adverse conditions. Slough is a type of necrotic tissue. It can essentially be thought of as a form of biological debris that’s made up of: 

• Fibrin
• Leukocytes
• Dead and living cells
• Microorganisms
• Biofilms (not always, but they can infiltrate)
• Proteins involved in skin structure and formation, like collagen and elastin 

Slough is also said to have complex microbial communities, particularly those comprising the Corynebacterium, Staphylococcus, and Pseudomonas species. However, what is included also depends on the wound’s etiology and its location on the body. 

Why Do Slough Wounds Occur? 

Research has found that necrotic death is nearly always linked to an inflammatory response, and interestingly, slough is primarily a byproduct of the inflammatory phase of healing. As a derivative of one of the initial stages of healing, though, it’s crucial to clarify that slough is not inherently a bad thing. It’s the body’s natural response to removing dead tissue and cellular debris. 

During the inflammatory stage, neutrophils are recruited to the wound site to combat infection and remove devitalized tissue. This specific action is the body’s attempt to clean the wound and prepare it for repair, which is beneficial. However, if those neutrophils die at a faster rate than they can be removed by macrophages, and begin stalling the healing process, the result is slough that causes dysfunction.

How Does Slough Affect Wound Assessment and Treatment? 

As mentioned, slough isn’t a singular, uniform entity, due to its wide range of textures, consistencies, colors, and more. It’s quite diverse, making wound assessments a challenging task for even the most experienced practitioners.  

Below, we’ll look at the different ways slough can impact initial and ongoing assessments, as well as wound care therapies. 

Hinders Wound Identification and Measurement 

Slough can partially or entirely cover a wound, making it difficult to stage a wound accurately. A good example of this is pressure ulcers. If you’re completing a wound assessment for a pressure injury and the underlying tissue is fully covered by slough, you won’t be able to assess the actual depth of tissue loss. In other words, you won’t be able to stage it, so it’ll simply be classified as an unstageable pressure injury. In many cases, the presence of slough can lead to misdiagnosis and, consequently, to inappropriate treatment. 

Slough Might Conceal Structures 

Think of slough as a fog over the wound bed. Just like fog reduces visibility, slough may also limit your ability to see exposed bone, tendon, or foreign bodies in the affected area. Its masking effects can underestimate just how severe a wound is, and if specialized treatment is needed that goes beyond slough removal.  

Slough Affects the Periwound, Too

Slough doesn’t just interfere with one’s ability to evaluate the wound, though. It might also make it challenging to observe problems with the surrounding tissue. For instance, if a practitioner notices slough, they might focus more on treating the wound bed itself than the periwound area. This could be an incomplete treatment, though, especially if the periwound is experiencing damage from dressing changes or shearing forces from the patient sliding down in bed. 

Slough could also overflow onto the periwound skin, compromising what would otherwise be healthy tissue. Due to their color similarity, clinicians might miss early signs of maceration or cellulitis. 

Practitioners May View Slough as a Surface-Level Issue 

Sometimes, slough is seen as a superficial problem, but it can be much more than that. For instance, let’s consider a patient with a deep tissue injury (DTI), which is often caused by prolonged pressure. They can remain invisible for up to two days and then progress rapidly as the damaged deeper tissue breaks down and rises to the surface, presenting as slough. 

In this scenario, a practitioner might only see the slough and classify the wound based on what’s visible to them. For context, let’s say they observe partial-thickness skin loss with slough and decide to classify it as a stage 2 pressure wound. By doing so, they’d be overlooking the extensive damage that occurred much deeper, which requires more advanced intervention. 

Additionally, slough is viewed as a local factor, but its presence may indicate an underlying systemic issue. An example would be if a patient suffers from impaired blood flow due to a cardiovascular condition. Poor perfusion can cause tissue death and lead to slough formation. It can also make it difficult for the body to clear away debris, thus causing a buildup of slough. 

Slough Is Often Confused with Other Substances 

Additionally, sometimes what appears to be slough may not be so. Slough shares similar characteristics to other wound bed substances, such as: 

• Eschar. Although eschar is typically dry, hard, and has a dark brown or black complexion, it could be softened or liquified due to excessive exudate, causing it to be mistaken for slough. 
• Fibrin. While included in and a part of the formation of slough, this blood clotting protein is its own entity. If mistaken for slough and debrided, practitioners would be removing the scaffold for new tissue and hindering wound healing. 
• Purulent drainage. Both can have a yellowish hue, and if viscous, pus may have a gelatinous texture similar to loose slough. 
• Granulation tissue. When unhealthy, it might be covered by white or yellow fibrous tissue, which some practitioners might mistake for slough. 

How Does Slough Affect Wound Healing?

Research indicates that necrotic cell debris is a strong trigger of inflammation, and since slough is basically debris, it’s safe to say it does the same. Although its initial presence is the result of the body trying to clean a wound, when it sticks around for longer than it’s needed, it can stall the healing process. This is why you’ll often see it in slow-to-heal wounds. 

Slough impacts the wound healing process in numerous ways. For one, it acts as a physical barrier, making it challenging for new, healthy tissue to develop. Furthermore, it keeps the wound stuck in the inflammatory phase, making it unable to progress through the remaining stages where the wound could eventually close. 

Additionally, slough is a reservoir for biofilms and microorganisms, which can cause inflammation and infections. Since slough attracts biofilm, and given that over 90% of chronic wounds contain biofilm, practitioners should prioritize the prevention of excess slough build-up to avoid creating an environment that allures bacteria.  

Common Slough Wound Treatment Methods 

If you want to encourage a slough wound to move from the inflammatory phase to the proliferative one, effective management is necessary. 

Desloughing, or the removal of slough, is a top priority, and debridement, which is the process of removing any non-viable, is the way it’s done. There are a variety of debridement methods practitioners can implement to promote proper wound healing. Those methods include: 

• Autolysis/natural desloughing. This approach uses the body’s natural defense system to actively break down damaged tissue at the wound site, using enzymes to digest components like proteins, fibrin, and collagen. 
• Enzymatic debridement. Collagenase, an exogenous proteolytic enzyme, is used to debride tissue by digesting collagen within the necrotic material, enabling its detachment. 
• Biological debridement/larval therapy. Sterile fly larvae are strategically placed in a wound to selectively remove necrotic tissue and aid healing.
• Surgical debridement. Involves excising necrotic tissue using a scalpel, curette, or scissors. It’s appropriate for both slough and eschar removal. 
• Mechanical debridement. This includes physically removing necrotic debris from a wound. Common clinical methods used are wet-to-dry dressing changes, hydrotherapy, monofilament pads, and wound irrigation.

Slough Wounds: A Guide to the “Gunk”

Compared to other local factors, like a wound site infection, excess exudate production, and mechanical stress, slough is under-discussed and even under-emphasized. Yet, as you’ve likely gathered here, more awareness is needed on this often misunderstood substance. 

We encourage you to use guides like this to help yourself and other wound care specialists identify and better manage slough wounds. However, we also recommend pairing your clinical acumen with AI-powered technological solutions to get the best results. Tools like advanced 3D wound imaging can make wound assessments more seamless, and predictive analytics can give you heads up on what’s coming next so you can be prepared for potential wound changes. 

It’s possible to leverage your team’s capabilities and achieve better outcomes, even when dealing with complex factors, like slough, when you incorporate a holistic approach that integrates both deep clinical knowledge and cutting-edge technology.