Recently, a baby girl was born in Columbia with a rare addition - a parasitic twin. But this was no ordinary parasitic twin. Incredibly, a smaller, undeveloped fetus was found growing in the abdomen of the larger baby.
What makes this birth even rarer was it was a 'fetus-in-fetu' birth, where a half-formed twin develops in the body of the larger twin. It was first recorded in a British medical journal in the early 19th century and occurs in about 1 in every 500,000 births. There have been similar births recorded in India, Indonesia and Singapore in recent years.
This most recent case was actually identified before the baby was born, which is also fairly rare. Dr. Miguel Parra-Saavedra, a high-risk pregnancy specialist, first saw the baby's mother when she was 35 weeks pregnant. At first, he believed that her baby had a cyst on her liver, but he soon realized something else was going on.
Through the use of a colour Doppler and 3D/4D ultrasound imaging, he was able to see that there was actually a smaller infant inside of the larger baby, supported by a separate umbilical cord.
Dr. Parra-Saavedra remembered explaining this to the baby's mother, Monica Vega, who refused to believe it.
"'What? No, doctor, this is impossible,'" he recalled Vega saying. He added that one he explained the situation to her "step by step", she finally understood.
On February 22nd of this year, doctors delivered Vega's daughter at 37 weeks by cesarean section. The very next day, they removed the underdeveloped twin - which was around 2 inches long and had a rudimentary head and limbs - via laparoscopic surgery. It was found to not have a brain and heart.
Dr. Parra-Saavedra believes that Vega's baby, named Itzamara, and her twin started out as identical twins, but his team is waiting on a DNA comparison before confirming. These types of twins, also called heteropagus twins, are born conjoined to their healthy siblings - either partially inside, or outside of their twin's body. The condition is thought to occur soon after day 17 of gestation.
Unlike little Itzamara, who is now doing well and whose condition was diagnosed while Vega was still pregnant, some heteropagus twins can go undetected for years. For example, in 2015, a 45-year-old woman underwent surgery for what appeared to be a 4-inch tumour on her ovary. Afterwards, the growth turned out to have a partially formed face and even hair. Doctors concluded that it was actually a twin she had absorbed while in her mother’s womb.