Doctors at the Children's Hospital of Philadelphia have performed more than 1,400 foetal operations since 1995, according to the hospitals, reports Live Science.

Dr Jack Rychik, director of the foetal heart program at the hospital, said: "The fetus was just about 6 inches in total length, and his heart was the size of a peanut, perhaps a centimetre or less."

However, he said operating on a foetus' heart is extremely risky and therefore rarely done. Most of the foetal operations performed at the hospital have been to remedy birth defects such a s spina bifida, not to operate directly on the heart.

But Dr Rychik told Live Science they made the decision to operate on the tiny heart because it was a matter of life or death. The tumour had grown to the size of a walnut – bigger than the heart itself – and was squeezing the tiny organ.

The mum, Cecilia Cella, has visited a paediatric cardiologist in her home town of Uruguay. Her doctor, Dr Roberto Canessa, texted a video of a sonogram of the baby to Dr Rychik asking for help.

Dr Rychik explained how he recognised the mass as an extremely rare but rapidly growing tumour called an intrapericardial teratoma. The tumours grow on the sack surrounding the heart and can place deadly pressure on it if it is not treated.

within a matter of days Cecilia and her husband, Pablo Paladino, flew to Philadelphia for surgery. Dr Rychik said: "Had we waited another day, I think it would have been too late.

Doctors removed the foetus' arms and shoulders from the womb so they could operate on his tiny heart. In order to operate on the foetus the surgical team put mum under anaesthesia and made an incision into the mother's uterus and drained the amniotic fluid.

They then further anaesthetised the foetus to make sure he remained still for the incredible surgery. They then delicately lifted the foetus' arms out of the uterus to access his tiny heart. Dr Rychik said: "By bringing the arms out and the chest up, [we ensure that] the chest is available to the surgery.

"Then, an incision is made into the chest and the ribs are cut as they would be in an adult." Docotors had to drain the amniotic fluid from the uterus in order to access the baby and replace with with artificial fluid later

Afterwards, they sewed up the incisions and put the foetus back in the womb. They then replaced the lost amniotic fluid with artificial amniotic fluid so the pregnancy could continue. The procedure took three hours but the surgeons were not able to cut away all of the tumour.

About two percent of it was too attached to the heart for them to safely remove it. The tumour did begin to regrow while the baby was still in the womb, but the surgery bought him vital weeks to develop before he was born.

The baby, named Juan, was born in December last year and underwent another surgery to remove the remainder of the tumour two weeks later.

He is reportedly doing well. Doctors wrote about the case, along with seven others from 2009 to 2015, in the American Journal of Obstetrics and Gynaecology.

However, in six of those cases the doctors could not operate and the foetuses died. In another, they were able to deliver the baby early and perform and emergency operation.

But before Juan, the Children's Hospital of Philadelphia team performed a successful heart surgery on another foetus in the womb.

Tucker Roussin is now three-years old. Juan and Tucker are the only two known foetuses to have undergone such a procedure.

READ the original story in the Sun here: https://www.thesun.co.uk/living/3268205/surgeons-remove-tumour-from-21-week-old-unborn-baby-still-inside-the-womb/