Doctors at the Vatican's pediatric hospital successfully separated conjoined twins whose skulls were fused back to back, in an exceedingly rare surgery for an equally rare congenital defect. The twins, Ervina and Prefina Bangalo, were born on June 29, 2018, in Mbaiki, the Central African Republic, with their heads attached and sharing critical blood vessels around their brains.

Twins conjoined by the skull are extremely rare, approximately one in every 2.5 million live births, the hospital said, adding that in Europe in the past 20 years there were only two successful cases of separating twins joined at the top of their skulls.