Hi Andy this is a worry...here is some info
First line of defence – Treatment:
Chickens that show signs of prolapse can be helped by preventing them laying. However, if there is any small prolapse gently push it back into the chicken with your fingers. The chicken should then be put on a maintenance diet of wheat and water and put in a dark cage. Leave the hen there for a week.
In severe prolapse a purse suture and maintenance diet with the chicken kept in the dark, as above, works well. However, it is important to restrict the chickens diet to maintenance only for possibly a couple of months. This does work!! Alternative to maintenance diet is feeding the chicken enough to keep it alive, moving and keeping warm plus enough extra feed for it to produce eggs.
You may find that by reducing the feed it brings on a forced molt
By reducing feed intake so that the bird has just enough feed to keep it alive, moving and keeping warm you are feeding for maintenance only. The chicken will not lay eggs and so give it the best chance of recovery.
You can try to push the prolapse organs back in, very carefully
First, remove the hen immediately from the flock to prevent cannibalism
Clean the prolapse organ
Which will have become dirty
Use warm water and a very mild soap
Smear with a lubricating jelly like Vaseline and very gently push the prolapsed organs back into the body cavity
Isolating the bird and reduce the feed to try and stop her laying
She more than likely she has another egg already moving down the oviduct
The next egg laid could cause another prolapse
Helping to prevent further damage when a hen is prolapsed
1. Reducing swelling and allowing the muscles to contract
2. Preventing a yeast infection
3. Preventing them laying
4. If there is any small prolapse gently push it back into the chicken with your fingers
5. Put the hen on a maintenance diet of wheat and water
6. Put in a dark cage to stop the laying cycle (5 days to 2 months (severe case))
7. In severe prolapse a purse suture may be need to the cloaca
Wash area with sterile water and using preparation-H (this is an ointment used for humans who have piles or hemaroids)
Coat the extended portion in and around the vent area.
Preparation -H reduces the swelling tissue and thus allows the tissue to recede.
If the bird is left in this condition, the other birds will peck at her, and she will become infected and fly blown, die from loss of blood or blood poisoning
You should cull the bird immediately if this happens.
Hope everything goes ok.