Sisters conjoined at the head are separated after 50 hours of surgery

Conjoined twins Safa and Marwa are recovering well after complex surgery at London's Great Ormond Street Hospital.

London (CNN)A pair of Pakistani conjoined twins are finally living independent lives after a 100-strong team of British medical experts spent 50 hours performing complex surgery to separate them.

Safa and Marwa Ullah came as a bit of a surprise when they were born in January 2017 as their mother had not known she was expecting twins -- let alone craniopagus twins, who are joined at the head.
Around two in five sets of craniopagus twins are stillborn or die during labor, while a third more do not survive the first 24 hours. Fortunately in the sisters' case, a wealthy benefactor offered to cover the costs of their long journey from home in Charsadda, Pakistan, for the surgery at London's Great Ormond Street Hospital (GOSH).
    According to its website, GOSH "is one of only a few hospitals in the world to have the infrastructure, facilities and team of experts" to separate conjoined twins. It has carried out the procedure more times than any other hospital worldwide.
      Born by cesarean section, the girls emerged with their skulls and blood vessels fused together. Since arriving in Britain, they have undergone three operations between October of last year and when they were finally separated on February 11.
      Such a procedure is extraordinarily rare; according to GOSH, the chances of craniopagus twins undergoing surgery is around one in 10 million. Around 5% of conjoined twins are craniopagus cases.
      After consultation with their doctors in Pakistan, the London hospital welcomed them to the Bumblebee Ward where various experts -- from craniofacial, neurology and psychology specialists, to nurses, radiologists and physiotherapists -- spent four months treating them.