Surgeons have mixed results in separating conjoined babies

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Indy Lifestyle Online

The incidence of conjoined twins in Britain may be as low as one in every 200,000 births.

The incidence of conjoined twins in Britain may be as low as one in every 200,000 births.

The twins originate when a single fertilised egg starts to split soon after conception, but the process is not completed and the partially separated embryo develops into a conjoined foetus.

As a result, the twins are always genetically identical and of the same sex, but there is no typical case. Where and how they are joined, the number of organs shared or joined, and how well the children are at birth varies widely.

Nearly three-quarters are connected at mid-torso, along the chest wall or upper abdomen, as in the case of the May twins. Of the remainder, about 23 per cent are joined at the lower torso with shared hips, legs or genitalia, and 4 per cent are connected at the head.

Fewer than two dozen sets of twins are known to have been dealt with at British hospitals in the past two decades and their survival has been heavily dependent on whether vital organs are shared. Great Ormond Street Hospital in London is by far the most experienced, having seen 17 sets of twins from Europe and the Middle East.

The survivors include only four complete pairs of twins. For five sets of twins, no operation was considered possible and all the children died.

In another seven cases, emergency surgery was carried out because one or both of the children were already dead or dying. Four children are still alive from these cases.

The remaining five sets of twins were sufficiently well to undergo a planned operation and eight of these children survived, although two subsequently died for other reasons.

The term Siamese twins arose after the birth of Eng and Chang Bunker in Siam in 1811. They were exhibited in circus sideshows around the world before settling in America, where they married two sisters. They lived to the age of 63, with Chang fathering 12 children and Eng 10.