PHILADELPHIA (CBS) — Children’s Hospital of Philadelphia is world-renowned for its fetal surgery in which an operation is performed on a baby still inside the womb.

Recently, in yet another historic procedure, CHOP doctors undertook a risky and delicate operation on a tiny fetal heart.

Health reporter Stephanie Stahl has the exclusive story of what it took to save an unborn baby named Juan.

After some setbacks, an excited family who learned they were finally going home to South America said goodbye to the team that saved their baby.

Baby Juan and his parents, Cecilia Cella and Pablo Paladino, are headed back to Uruguay where the infant has become a celebrity.

“We receive calls, messages from people we don’t know,” said Pablo Paladino.

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Since October, the family has been camped out at CHOP where doctors saved little Juan’s life with an intervention that is largely unheard of in many places.

“It was a hard time, crazy time, but we are extremely happy how everything was solved,” said Paladino.

When Cella was five months pregnant, a routine ultrasound showed a mass on the baby’s heart.

Their doctor in Uruguay sent the images to his friend, Dr. Jack Rychik, who is the director of the Fetal Heart Program at CHOP.

“The minute I saw this I recognized there was a giant tumor sitting on the heart,” said Rychik.

It was a rare pericardial teratoma and the only hope was fetal surgery where doctors would operate on the baby Juan’s heart inside the womb.

“We never heard this before,” said Paladino.

“I started laughing, like what, they do that,” said Cella.

The family raced to Philadelphia because CHOP is the only place where the risky fetal heart operation has been done successfully on just one other occasion.

“We’re operating on two patients here with the single intent,” said Rychik. “Our goal is to get to the tumor and resect the tumor but we also have mother and baby.”

Juan is now the second baby to survive the fetal surgery.

The procedure was performed when his mother was 21 weeks pregnant with the baby.

“His heart at the time of surgery was the size of a peanut. The size of the tumor was three-times the size of the heart,” explained Rychik. “Had we waited an additional day, we probably would have been too late.”

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After the fetal surgery, the pregnancy continued as the family waited in Philadelphia.

At 31 weeks, Juan was born on Dec. 11, but the tumor had grown back so there was a second heart surgery.

“There were a lot of chances the baby was going to die,” said Paladino.

And now, with a big scar on his chest, Juan is 3 months old and healthy.

However, his prognosis is unknown.

“There are no other human beings alive today who have had fetal surgery for this removal of this type of tumor that are 30, 40, 50, 60 years old. We could then say what the prognosis is going to be,” says Dr. Rychik.

But for Cella and Paladino, at least their son has a chance after the fetal surgery that still has their heads spinning.

“Crazy, unbelievable, I look at him, I can’t believe what they did here,” said Cella. “It’s awesome.”

“We are grateful that we came here,” added Paladino. “The doctors are amazing.”

The family is now back home in Uruguay where little Juan continues to thrive.

The tumor that was on his heart was benign.

It’s unknown as to what causes this type of tumor, but it is usually a fatal condition.