Conjoined twins, also known as Siamese twins due to the famous brothers Chang and Eng Bunker, are a medical mystery. It is still unknown why monozygotic twins enter the world conjoined. Today the diagnostic can be revealed in the twelfth week of pregnancy. Although a medically interrupted pregnancy is advised some parents decide to keep their children. In January 2019 The New England Journal of Medicine (NEJM) reported the successful operation to separate two twins joined at the head. Let’s have a look more closely at the conjoined twins and their operation.
Risky operation was a success
Two little girls Abby and Erin were separated at the age of ten months old in an operation in 2017. The NEJM journal reported the operation in detail this year in 2019.
The twins were born with a total cranial fusion (craniopagus) meaning a complicated operation was necessary to separate the two young girls. Although many conjoined twins are joined in the upper area of the body (40% of cases), the girls condition was very rare amounting to only 2% of cases.
Despite multiple technical and medical advancements in today’s society many complications could arise after an operation like this. Abby and Erin required a multidisciplinary team to carry out the operation in order for them to be separated with success. The operation involved 30 people from surgeons, nurses and specialists and took over 11 hours to complete. Each specialist team was in charge of portion of the operation so that the operation could be carefully completed with the most highly skilled people for each section.
The two young girls needed to wear a contraption that helped to separate them as much as possible from one another. A circular device between their two skulls separated them millimeter by millimeter. Once the right distance has been reached, the operation could then take place.
The doctors made a computer generated model of the girls head so that they wouldn’t make any mistakes. This digital tool allowed them to digitalise each bone, vein and blood vessel. This was the one of the biggest problems of the operation. As the two girls were perfectly conjoined one of the biggest veins of their brain which was stocked with blood and oxygen was also connected. That being said, surgeons managed to separate the two girls successfully. Despite postoperative complications, both girls, now two and half years old, are doing very well today and have a relatively normal development.
What are conjoined twins?
How is it diagnosed
Currently there are no exact explanations for why some twins are born joined to one another. Conjoined twins are born without us really understanding why. There is no genetic link or environmental factor so it is hard for experts to pin point one factor. Nevertheless it is possible to find out if you are carrying conjoined twins from the twelfth week of pregnancy.
A deeper study is carried out when an ultrasound scan shows that:
- It is a monochoral twin pregnancy (the twins share the same placenta)
- Babies keep the same posture, are mirrored or have scoliosis (deformity of the back),
- The twins share the same umbilical cord,
- Visible adhesion of the babies.
This further exploration can find out whether several organs are connected to one another. If the twins’ heart is connected, a medically interrupted pregnancy is necessary.
In the 1990s, Rowena Spencer from the University of Medicine in Louisiana describes different types of Siamese children and classes in two main categories. Conjoined twins connected by the back (dorsal junction) on the one hand and those connected by the belly (ventral junction) on the other hand.
The dorsal junctions
- Craniopagus: connected at the level of the head
- Rachipagus: connected back to back
- Pygopagus: connected by the sacrum, the coccyx or the perineum.
- Cephalopagus: babies have fused from the top of the head to the navel (no survival possible)
- Thoracopagus: connected to the thorax (rare survival beyond three months)
- Xiphopagus: : connected laterally to the level of the thorax liver;
- Omphalopagus: connected by the lower thorax to the navel
- Ischiopagus: the twins are often born opposite each other and fused by the pelvis. They can have two, three, or four legs for both of them.
- Parapagus: connected on their side with a fusion of different parts of the thorax, skull and pelvis.