An important element in wound assessment, care planning, and documentation is the distinction between slough and purulence. Slough is necrotic tissue that needs to be removed from the wound by debridement for healing to take place, whereas purulence, or the presence of pus, may be seen in patients with signs and symptoms of infection.

https://www.woundsource.com/blog/assessing-wound-tissue-and-drainage-types-slough-versus-purulence