Yes, my Moluccan cockatoo had this for years!! She was not born healthy, she had some other medical problems, but as she got older she also developed a prolapse. I just lost her last week and I'm still in mourning...(she did not pass from the prolapse so don't worry). Over the years I've taken her to the best avian vets in my area and they all did "pexi's" on her. Eventually she blew them out and re-developed the prolapse. I even took her to Avery Bennent in Gainsville, FL reported to be the best of the best. His surgury lasted the longest - 3-4 years. Toward the end, I switched tracks and went to a holistic vet. She's been on herbs and getting vitamin B shots. Believe it or not, she was responding great. However she did pass last week and I think with all her ailments, she just finally got weak. She was only 12 which is pretty young for a Moluccan.
My final commments are - they can live a long time with a prolapse, and surguries usually work (I'm sure I had the exeception...all the vets where baffeled as to why she kept blowing it out). It looks bad to see it, but it is not the end. Your bird will definetely need surgery though and keep your eye on it. Thanks, Renee