Conjoined twins - DOC by xiangpeng


									Conjoined twins

Siamese twins are very rare
Siamese, or conjoined, twins are extremely rare, occurring in as few as one in every
200,000 births.

The twins originate from a single fertilised egg, so they are always identical and of
the same sex.

The developing embryo starts to split into identical twins within the first two weeks
after conception.

However, the process stops before it is complete, leaving a partially separated egg
which develops into a conjoined foetus.

The birth of two connected babies can be extremely traumatic and approximately 40-
60% of these births are delivered stillborn with 35% surviving just one day.

The overall survival rate of conjoined twins is somewhere between 5% and 25%.

Historical records over the past 500 years detail about 600 surviving sets of
conjoined twins with more than 70% of those surviving pairs resulting in female

If they have separate sets of organs, chances for surgery and survival are greater
than if they share the same organs.

Conjoined twins are generally classified three ways:

        73% are connected at mid torso (at the chest wall or upper abdomen)
        23% at lower torso (sharing hips, legs or genitalia)
        4% at upper torso (connected at the head)

Over the years, survival rates have improved as a result of more accurate imaging
studies and better anaesthetic and operative techniques.

The term siamese twins was coined as a reference to Eng and Chang Bunker, who
achieved international fame following their birth in what was then Siam in 1811.
They were exhibited in circus side shows around the world before settling in the
United States and marrying two sisters. They lived 63 years, with Chang fathering 12
children and Eng 10.

In the UK an annual celebration was held for centuries to commemorate 12th
century siamese twins Mary and Eliza Chalkhurst, wealthy sisters who bequeathed a
fortune to the church.

Aiofe and Naimh McDonnell, from County Kildare, were born in June 1997 sharing a
liver, kissing each other because of the way they were joined.

Surgeons took seven hours to separate them in an operation at Great Ormond
Street. The twins are now living a healthy life in Ireland.

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