Overview of Conjoined Twin Separation Surgery

Twin separation surgery (for conjoined twins) often hits the news, involving numerous doctors and hours. Ever been curious about what exactly a surgery like this entails?

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Understanding Conjoined Twins

Twin separation surgery occurs when doctors separate twins who are born conjoined at birth. Conjoined twins are attached together, both inside their bodies by sharing certain organs or body parts, as well as outside through the skin. They are usually identical twins, meaning they will be the same sex. Conjoined twins are actually very rare, considered to be about 1 in 50,000 to 100,000 twins worldwide.

When two twin babies are fused together at the same place, they are called symmetrical twins. In some cases, one of the conjoined twins may not actually be alive and is instead called a "parasitic" twin. One twin may be normally developed and able to live outside of the womb, while the other twin does not develop properly in order to sustain life.

Female twins are more likely to be conjoined symmetrical twins, while male fetuses tend to have more cases of parasitic twins. Although doctors aren't sure why, female conjoined twins also tend to have a higher chance of surviving. Sometimes, both twins may also be incompatible with life as a result of the abnormal development and fusion. Conjoined twins, if they survive birth, are also at risk for many health complications and problems.

What Is Twin Separation Surgery?

Twin separation surgery for conjoined twins can be different, depending on how exactly the twins are conjoined. For example, some twins may share a digestive tract or a part of their circulatory system. The more intricate the affected system is, the harder the surgery may be.

According to the University of Maryland, there are almost twelve different classifications of conjoined twins that will determine what type of surgery is needed. Twins may be conjoined in their upper bodies and share a heart, which makes it almost impossible to perform a successful surgery. Other types of twins may share an upper body and certain organs, such as a liver or GI tract, but not the heart, making surgery a more realistic option. The rarest type of conjoined twins is craniopagus twins, who are connected at the head.

Historically, twin separation surgery was not an option and conjoined twins who survived birth remained connected throughout their lives. For example, one of the most famous sets of twins was Eng and Chang Bunker. The brothers were born in Thailand, which was called "Siam," in 1811, and the fact that they remained conjoined eventually led to the term "Siamese twins." That term, however, is no longer used as conjoined twins have nothing to do with where the babies are born.

What Is the Outcome For Twin Separation Surgery? 

The outcome for twin separation surgery will depend on how and where the twins are connected. Unfortunately, a doctor can not tell the degree of fusion until the babies are born, so any decisions and specific details about what kind of surgery is necessary have to wait until after the babies' birth.

In one study that followed fourteen twins who were separated by surgery after birth, four twin sets had both twins survive and those four twin sets required more than one surgery before separation was completed. However, all of the twins in the surviving sets were followed by doctors and showed appropriate and normal development. Although in some cases, twins who are separated may need extra help or therapy in their spines especially, since many of them didn't form properly.

As technology has advanced, more conjoined twins are able to benefit from twin separation surgery without any major complications.

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