Monday update about 6:30 PM
Again thank you all for responses and advice.
After a visit to the vet today, they are in fact maggots apparently from fly strike as described. The wound however while immediately adjacent to her vent is not from the vent. The vet says it is a tumor which expanded and burst out, and that the tumor has been there for a significant amout of time. Exactly how it burst is not know, but the burst created the wound that the flys hit.
We have some meds and care instructions and we'll see where this leads after a few weeks.
Just to spread awareness, we first noticed this on Friday evening 5 Sep, thinking the hen had diarriaha. What we thought was dried manure on her feathers was in fact dried blood. Saturday morning while preparing for TS Hanna I checked the coop, the hen was on the roost allowing me to get a good look at her when I saw the wound. Reading posts here and looking else where led me to think it was a vent issue. While trying to execute the remedies I had read I spotted the maggots. The rest of the story is in the this thread of posts.
We'll do what the doc said and I'll update as this progresses. On a good note though she is acting pretty much normal today and well within her normal charecter. We have her seperated from the flock to prevent the others from pecking at her.
Thanks
JP