An operation to separate Costa Rican conjoined twins yesterday in California was deemed successful by doctors, according to a press release from Lucile Packard Children's Hospital, where the procedure took place. But more complicated surgery remains ahead.

The twins, Yurelia and Fiorella Rocha Arias, were joined at the abdomen and chest. The two-year-old girls shared a liver and part of their heart.

Later this week, a cardiothoracic surgeon will operate on Yurelia's heart, which suffers from a debilitating condition.

The girls' procedure has drawn attention from the Costa Rican media as newspapers and TV news channels have followed their progress. They are the first conjoined twins in the country to be separated, reported the daily La Nación.

Moreover, one of the doctors on the team, Carlos Esquivel, is Costa Rican.

Mending Kids International, a California-based organization, covered the cost of both parents accompanying the girls.

The lead surgeon on the team, Gary Hartman, had estimated the girls' chance of survival after the first surgery to be 50%.

“The separation is the culmination of months of planning by several multidisciplinary teams,” Hartman said in a statement. “It was a very risky and complicated surgery, and the outcome is still unknown. The girls face many more hurdles in their path to recovery.”

-Tico Times