Twin girls, joined at the skull, successfully separated in 18-hour operation in Vatican hospital

The twins, Ervina and Prefina, pictured with their mother, Ermine.

(CNN)A pair of conjoined twin girls with an extremely rare condition have been successfully separated at a hospital in the Vatican City.

Ervina and Prefina, aged 2, were joined at the skull before an operation that lasted 18 hours and involved 30 doctors and nurses, according to a press release from the Bambino Gesù Pediatric Hospital published Tuesday.
The separation took place on June 5 and the girls, who are from the Central African Republic, are expected to make a full recovery.
The girls shared a skull and a majority of blood vessels.
This is the first time that doctors in Italy have successfully separated conjoined twins in total posterior craniopagus, which means they shared a skull and a majority of blood vessels.
There are no other cases of a successful intervention described in medical literature anywhere else in the world.