Singapore has announced its doctors will perform an unprecedented operation to separate Iranian Siamese adult twins joined at the head. The doctors and sisters decided to go through with the medical procedure despite the high risk of death.

After six months of exhaustive tests and the approval of a medical ethics committee, doctors at Singapore's Raffles Hospital said Monday Laleh and Ladan Bijani will undergo the risky surgery to physically separate the twins.

Dr. Keith Goh, the neurosurgeon who will lead the operating team, says he believes the surgery is feasible although adult twins have never been separated before. "In terms of answering the question within myself as to whether the surgery was justified and whether we should go ahead," he says. "I think as we got to know the girls better and spent more time with them together with out counselors and psychiatrists, we were convinced after a few months that this decision was sound and that, based on the quality of life issue now, it was the correct thing to do."

After years of searching for the right medical team, the sisters say they are nervous but excited for this chance at independent lives. Both lawyers, who graduated from Tehran University, they would like to pursue different paths. Laleh wants to practice law while Ladan hopes to further her education.

The twins have undergone two months of psychological counseling and testing to make sure they were mentally competent to make the life-changing decision and understand the risks.

Dr. Goh says one or both of the women could die or end up in a vegetative state, but all are hoping for the best. Devout Muslims, the Bijani twins believe the outcome of their surgery is the will of God.

The women are joined at the side of their heads, have separate brains - but share a single cranial cavity and a common vein, which carries blood back to the heart.

The medical team will include 12 surgeons - specialists from the United States, France, Japan and Switzerland. The separation operation has been scheduled for the first week of July and could take up to four days to complete.

The doctors are waiving their professional fees while the hospital is underwriting the twins' stay. It is estimated the other medical and non-medical expenses will amount to $290,000.