eggbound with maggots & blood in vent - had to euthinize

I've been away at work for the last couple days. When I came home this morning and checked my coop, one of my older RIR was laying in a corner, limp not moving. I picked her up and immediatly noticed a bunch of goo coming out her rear end. I took her to the hose and washer her butt off and got a better look. Out of her vent I noticed more yellow goo oozing out and then I noticed some maggots coming from her vent.
Long story short, out of her vent I pulled some broken shells and more maggots. I kept flushing and pulling out egg shells and maggots, and eventually blood started trickling out her vent. It got so bad and it seems I was hurting the hen more by pulling shells out, so I decided to euthinize her.
I feel bad for not catching this earlier. She was fine when I left 3 days ago. My DW said she didn't notice her laying in the corner while I was gone. This had to be going on for a while for maggots to get in there and hatch. Is there anything I could've noticed or done to catch this earlier?
Do I need to worry about my other girls? or is this just and isolated problem. This RIR was one of my two girls that did lay x-large/jumbo eggs every 2-3 days. Is this an inherient problem with jumbo egglayers and do I need to keep an eye on her sister.

Aloha,
Cory