I have not heard of this diagnosis pelvis separation. In the past (many decades ago), if there was a contracted pelvis, and the woman presented to the doctor late in labour, the cartilage between the pubic bones was cut to separate the pubic bones (front part of pelvis) to get more space, and thus help in delivering the baby vaginally. The aim was to avoid the complications of a performing a caesarean section too late in a place where facilities and expertise for this major operation were not available, especially when the chances of survival of the baby were negligible or the baby was already dead. In my 35 years in the medical profession, out of which almost 30 years are in Obstetrics and Gynaecology in India, I have not performed, nor seen any obstetrician performing this operation. This is mainly because of the good antenatal care, and the advances in medicine that have made caesarean section safe to both mother and baby. I suggest you ask your treating doctor what his plans are for you.