AUSTIN, Texas  - Surgeons in Texas have successfully separated 10-month-old conjoined twins fused at the waist who shared a colon and bladders, a hospital said on Wednesday.

The surgery at Driscoll Children's Hospital in Corpus Christi took about 12 hours to complete, resulting in the separation of Ximena and Scarlett Hernandez-Torres, the hospital said.

The pair have an identical triplet sister named Catalina, who was born without serious health issues. The incidence of a triplet birth involving conjoined twins is believed to be about one in 50 million, the hospital said.

A team of physicians including specialists in pediatric surgery, plastic surgery and urology had been preparing for months to carry out the complex and intricate procedure, which took place on Tuesday, it said.

The girls will remain in the hospital until they recover.

"They haven't lost a lot of blood, everything is going smoothly," the twin's father Raul Torres, 26, was quoted as saying by the Corpus Christi Caller-Times.