Yellow on a wound can mean two different things, and the difference matters.
As dead tissue in the wound. Pressure sores can be covered in dead skin that is yellow, tan, green, or brown. The dead skin makes it hard to tell how deep the sore is, which makes the sore unstageable. A venous ulcer can be a shallow sore with a red base that is sometimes covered by yellow tissue. This kind of tissue is called slough.
As drainage coming from the wound. Here yellow is one of the things to report. Contact your provider if drainage becomes thick, tan, green, or yellow, or smells bad — that is pus. With leg ulcers, drainage that is yellowish or cloudy is a sign to report. For any wound, contact your provider right away for yellow or green pus.
So yellow tissue sitting in the wound bed and yellow fluid coming out of it are two separate things. When you report it, be clear which one you are describing.
For comparison, here’s what the wound bed should look like: after cleaning or debridement the area will be red or pink and look like fresh meat. Wounds that are pale, purple, or black are less likely to heal.
If it is dead tissue, it’s clear what happens next and who does it. This tissue must be removed to help your wound heal — and you should never try to do this yourself.
If it is drainage, the useful details are whether there is more of it than before, and whether it smells. Both are signs to report.