Thanks for @Eggcessive for pointing out that is does look like she has "2" Vents.
The very bottom one (I call secondary with a red arrow) - does anything come out of that? Poop or fluids or anything?
The area with the "wound" to me is her "active vent".
From what I see in the photo and from my own experience with my hens and from here on BYC, at some point your hen suffered a prolapse.
The tissue when it was prolapsed was damaged somehow, likely from picking. You can see the top edge of the Vent.
The middle portion, I'm thinking is the opening to the Oviduct unless you are seeing poop come from that opening. The yellow is exudes/pus or material coming from the oviduct, could be a mix of albumen, calcium, lash material - hard to know. I do know that the yellow will stick like glue, just like the white urates do.
Mineral oil does help loosen the material a bit.
The yellow crud will need to come out and be removed in order for the oviduct to go back into place (hopefully).
What you are seeing, my best guess without feeling/seeing it myself is still a partial prolapse with some damaged tissue showing around the edges.
It would squeeze like a sphincter, since that's basically what it is.
I have added a few images/thoughts below too.
Bear with me.
Take a look at the image below.
See that the Oviduct (Uterus/Shell Gland), Vagina end at the "Cloaca" (Vent).
See that the Large Intestine also ends/connects to the "Cloaca" (Vent).
These 2 things are trying there best to either prolapse or be retained. I think once you get the yellow crusties removed and the oviduct cleared it may all go back in on its own.
Hopefully I'm seeing this correctly - anyone that has other thoughts/suggestions or sees something I'm not please chime in!
