There is no cure, no prevention. It's genetic/hormonal and common in high production breeds. Olivia and Tux are the first non-hatchery girls who've had this here. I've lost 8 to it so far.
It's hard to diagnose--I've just been through this so many times now that I am alert to it- it starts when the bird keeps going to the nest, sits, no egg. This happens over and over--this is happening with Tux right now. Eventually, she quits going to the nest. The abdomen can fill with fluid/yolk/infection and be huge and tight, but sometimes, gunk backs up just in the oviducts,which you won't know unless you open her up when she dies. The hen eventually loses an alarming amount of weight (you have to pick them up to really notice it), then becomes weaker and weaker, then either we euthanize them or they pass away on their own. If you read my thread about Ivy, she rebounded twice, but it is chronic and will eventually kill the hen, no matter what.