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  • Writer's pictureCork Medical

Slough or Purulent Wound Drainage: How to Tell the Difference

Identifying Slough

To achieve the best healing result for a patient, you need to be able to accurately assess the wound then determine which is the right course of action for treatment. A key ingredient used in this recipe for success is assessing if the wound bed is plagued with wet necrotic tissue, also known to be slough, or dry necrotic tissue. As you conduct your investigation, first identify if the wound bed shows signs of slough. This can easily be determined if the wound has a stringy texture, is yellow or white in color, and is moist in nature.

A common remedy for treating slough is debridement. Below are the most common debridement treatments to use on slough tissue.

But as debridement occurs, slough will naturally liquify causing clinicians to incorrectly document this as purulent drainage. An easy way to determine if the wound is still exhibiting signs of slough and not purulence is the odor. Wounds generally give off an odor while draining, so it’s imperative to remove and dispose of the old dressing first then cleanse the wound thoroughly before documenting the wound’s state. After completing this step and the wound continues to emit and odor, then it’s appropriate to document the wound as malodorous.

Purulence and Infection

If a wound is exhibiting purulence, it’s more than likely plagued with pus indicating an infection. An easy way to identify the signs and symptoms of purulence infection are:

  • Erythema

  • Odor

  • Redness that does not improve with elevation of affected limb

  • Pain

  • Changes in drainage (color, thickness, and amount)

  • Fever, chills, nausea, vomiting (systemic)


Determining if a wound bed is plagued with slough, purulence, or sometimes both can be challenging but cleansing the wound bed thoroughly before making any observations or conclusions will help to differentiate which wound type you are encountering.

Slough will always show signs of stringy textures, yellow coloring, and will be more granular after cleansing. Purulence will always emit an odor after cleansing and will show signs of infection and erythema.

When in doubt, consult with the Cork Medical wound care team for further evaluation. Contact us at 866.551.2580 or complete our request form.

Other helpful tips to keep in mind when examining the wound bed:

  • Anytime there’s intact eschar, including on the edges of a heel, do not remove or debride it. Keep the eschar dry, stable, and reduce any pressure surrounding the eschar. Then contact a podiatrist or vascular specialist for further assistance.

  • Slough has never been present in stage II pressure injuries, only in stage III or higher pressure injuries. But it can be found in other wound types such as vascular ulcers or diabetic ulcers.

  • In the case of slough or purulence, you’ll unlikely find biofilm. Typically, biofilms are present in chronic wounds and are not visible to the naked eye.



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