Twins stable, showing good vital signs 

Source: ONE NewsOne of the conjoined twins

Twins Trishna and Krishna are in a serious but stable condition at Melbourne's Royal Children's Hospital as they begin their second full day apart after life-saving surgery to separate them.

The girls, discovered in an orphanage in Dhaka, Bangladesh, in 2007, remain in a coma but were recovering well late on Wednesday, hospital spokeswoman Julie Webber said.

"They are doing well. They are stable and are showing good vital signs," she told AAP.

They are expected to wake up over the next 48 hours and it is only then that doctors will start to gain an idea of the success of the separation.

The hospital has stuck to forecasts before Monday's operation that the twins have only a 25% chance of complete recovery, a 50% chance of brain damage and a 25% chance one of them will die.

But their guardian, Moira Kelly, says her girls have defied the odds in surgery that she described as "a miracle".

"To see these two beautiful little people, two brave, brave little girls ... and I'm in the middle of them," a tearful Kelly told reporters on Wednesday.

"I can't comprehend, it's like being in the twilight zone.

"They are so good and looking really good.

"They are in two cots and I was standing in the middle of them, which is something I've never done before - it's amazing."

Kelly, the founder of the Children First Foundation, was instrumental in bringing the conjoined twins from the orphanage to Melbourne in December 2007.