By Stephanie Stahl

PHILADELPHIA (CBS) — High-tech science helped doctors in England successfully separate conjoined twins. Surgery to separate conjoined twins is complicated and dangerous but the team in England used cutting-edge virtual reality and 3D printing to plan the separation.

The 2-year-old conjoined twins, Marwa and Safa Ullah, from Pakistan, were known as craniopagus twins, which means they were born with connected skulls.

“What we need to achieve is to effectively, sort of, untwist the brains, and that is difficult, pretty difficult to do just in your head,” said consultant pediatric neurosurgeon Dr. Owase Jeelani.

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Doctors performed the complex surgery in three stages over five months at a children’s hospital in London.

Surgeons used virtual reality to see inside the twins’ heads in order to practice before the first cut and used a 3D printer to create models of the girls’ brains.

“For surgeons, it’s massively helpful to actually be able to touch and hold things, it makes so much of a difference to understand how things are,” consultant plastic and reconstructive surgeon Dr. David Dunaway said.

Each sister supplied the other’s brain with blood. Doctors first had to separate the shared blood vessels, then insert a piece of plastic to keep the brains and blood vessels apart.

“The last two months after their last operation on the brain has been a little bit of a stormy time for Safa and Marwa, but they’re hanging in there,” Dunaway said.

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Now that the twins are successfully separated, their mother is overwhelmed, saying she is very happy, especially to be able to hold them separately, even though doctors say the twins have a long recovery ahead.

The twins’ surgery lasted 50 hours, and doctors expect them to have some learning disabilities.

The surgery was made possible with what is being called generosity from a private donor.

In the United States, the Children’s Hospital of Philadelphia is world renowned for separating conjoined twins.

Stephanie Stahl