Siamese twins Abby and Erin Delaney born joined at the head and given a 2% chance of survival prove doctors wrong
Conjoined North Carolina twins who survived separation surgery despite just a two percent chance of survival have graduated kindergarten.
Abby and Erin Delaney, 6, were born at 30 weeks in July 2016, conjoined at the head due to a one in a million developmental condition that occurs when an early embryo only partially separates in utero. They weighed just six pounds combined.
In June 2017, the girls underwent an intricate 11-hour procedure to separate their skulls at Children’s Hospital of Philadelphia (CHOP). Despite low odds, the operation was a success.
The girls now have developmental delays, but their mother, Heather Delaney, said they are both thriving as they approach their seventh birthday.
‘Watching them graduate, it was like we were dreaming,’ Ms Delaney, 33, said. ‘It’s one of those things where you feel like it’ll never come.’
‘We don’t yet know what they can accomplish, so the sky is the limit for them.’
Twins conjoined at the head are known as craniopagus conjoined twins. Doctors told the Delaney family that the chance of having craniopagus twins was one in 2.5 million. According to CHOP, it’s the least common form of conjoined twins, accounting for about two percent of cases.
About 70 percent of these children are female, and in the case of craniopagus twins, they are always genetically identical and share the same sex.
It’s unclear what exactly causes conjoined twins, but there are two theories. One is fission, in which an early embryo splits into two spheres but doesn’t completely separate. These spheres then develop independently into conjoined twins.
The second theory is fusion, in which an identical twin pregnancy contains two early twin embryo spheres that merge and join at a random point.
About 40 percent of these twins are stillborn, with another 33 percent passing shortly after birth, often due to organ failure and other abnormalities.