Australian doctors successfully separated joined-at-the-head Bangladeshi twins after more than 24 hours of surgery on Tuesday, saying the girls were "in great shape" but faced a difficult recovery.
Two-year-old Trishna and Krishna, rescued from certain death in a Dhaka orphanage, were placed in induced comas after leaving the operating theatre unattached and spent the night in separate beds for the first time.
"The moment of separation was a rather surreal moment," Leo Donnan, chief of surgery at Melbourne's Royal Children's Hospital, told reporters.
"There was relief but I think everyone realized there was still a long way to go and that the girls have a very difficult time ahead of them."
Doctors worked through the night to prise apart the twins' brain tissue at about 11:00 am (0000 GMT) before reconstruction experts closed up their heads using bone and skin tissue, some 32 hours after they were wheeled into the operating room.
"The girls have now come out of the theatre and they're in intensive care," Donnan said.
"Everything's gone very well. They're in great shape which is fantastic... they're both in good condition and healthy. I think they're better than we thought they'd be."
The girls will spend the next few days sedated, on ventilators and under close monitoring before being gradually woken up, Donnan said, adding they faced myriad possible dangers.
"There are still considerable risks they've got to face, like any child who's been through a major procedure," he said. "They've got a long recovery ahead of them and there are many unknowns after this sort of surgery."
Moira Kelly, the girls' legal guardian who brought them to Australia from Bangladesh, was said to be overcome by the day's dramatic developments. The twins' miraculous journey
"I think she's overwhelmed this has come to fruition," said Margaret Smith, her colleague at the Children First Foundation charity. "She's just so grateful to the team here that they've been able to pull this off."
Some 16 specialists worked through the night, taking occasional food and rest breaks and listening to pop music in the operating theatre to stay alert, as the operation ran hours past its scheduled midnight finish.
Donnan said there was quiet elation among the surgeons when they finally separated the girls.
They were brought to Australia in November 2007 after spending their first few months in the Mother Teresa home in Dhaka, where aid workers became alarmed at their fading health and doctors said they were powerless to help.
But they were nursed back to health, developing a unique system of crawling on their backs and a love of Australian children's band "The Wiggles", as they underwent a series of preparatory operations.
"These are once-in-a-lifetime operations that teams would do. For the hospital it's a historic moment, for the girls it's an even more historic moment," Donnan said.
But Donnan said it may not be known for "a long time" whether they had sustained brain damage, so now was not the time for celebration.
"Doing operations like this... you are guarded. Everyone will be very pensive at the moment," he said later.
"There is no one moment of great celebration. There's relief and it's nice to know that we're onto the next stage," he told reporters.
"We've got a lot of unanswered, unknown territory we are moving into but all I can say is that everything is in place for the best possible outcome.
"Every step is an improvement."
The Mother Teresa home's senior nun Sister Olivet said extra prayers were said during the operation.
"We are still in touch with them and we have been kept informed of the progress of the operation. Yesterday everyone in the home took turns to pray for them," she said.
"Everyone remembers these children. They are very special children and we have many photos of them around the home so we can remember them. It's wonderful news."
Separating conjoined twins is a notoriously difficult procedure, with attempts in Britain and Bangladesh both failing over the past year, although Saudi doctors successfully divided a pair of Egyptian brothers in February.
In one of the best known cases, Singapore doctors in 2003 made a vain attempt to separate adult twins, Iranian law graduates Laleh and Ladan Bijani, 29, who died from severe blood loss after 52 hours of surgery.