Surgery to separate conjoined twins has been called off because the medical risks to the 3-year-old girls is too high, Rainbow Babies and Children's Hospital said Monday.

The decision regarding Tatiana and Anastasia Dogaru was announced by Dr. Nathan Levitan, chief medical officer of the hospital's parent, University Hospitals Case Medical Center. The decision complied with the wish of the parents to avoid any procedure that could harm either girl.

While the girls can develop life-threatening complications if they remain conjoined, the risk of proceeding with long-planned separation surgery was too great, Levitan said.

The blond girls have already beaten the odds by living this long. Most twins joined at the head die at birth and just 10 percent survive to age 10, according to the hospital.