Wishing you well!! My mum had this with my twin sisters. Mum was admitted into hospitail at 17 weeks preggers, as she also kept going into early labour. However, Ashley and Carley where born at 24 weeks prem. I still remember how tiny they were. Because of the twin to twin transfusion, Carly took most of the blood and her little heart could not cope. She left us 15 hours after birth. Ashley was a fighter though. She stayed in the hosp for 4 and 1/2 months and then mum got to take her home. Though we guess she missed her sister because not long after being home, and sadly 12 days before christmas, Ashley passed away via cot death.
That was ten years ago now, and mum never got the surgery you are talking about. So fingers crossed for you and your children, and all should be well as medical science has come a long long way!!!!