英语流行话题听力:Unit88 连体婴儿
Unit 88
Siamese Twins
Siamese twins are formed from a single egg which develops into two almost separate parts of cells. Normally, each part becomes an identical twin. However, cells in Siamese twins become confused about where they are in the body -- indeed which of the two Siamese twins they are actually in.
In normal fetus development every cell knows where it is in the body because the neighboring cells produce chemical messages. So a skin cell knows not only it is skin, but that it is, say, nose skin, rather than chin or ear or lip skin. In Siamese twins these chemical messages don't work properly -- ho can they? The end results can be very odd: a single organism with two heads, tow hearts, four legs and arms -- or is that single organism actually two people, two individual Siamese twins?
Although at first sight each appeared to have a separate well-formed body with some joining at the lower body, detailed tests showed these Siamese twins were very unequal. In some cases, one was providing the heart, lungs and many other basic functions. The other Siamese twin was vey poorly equipped for separate life. To make matters worse, these Siamese twins were to some extent dependent on each other. If separated, the stronger and more capable Siamese twin would need huge amounts of surgery over the following years, and was likely to suffer significant handicap.
It is a brave doctor indeed who is willing to take the knife to two Siamese twins, both of which are at that point alive and growing, and see perhaps both Siamese twins die in the operating room or very shortly afterwards. It is easier to go ahead if the parents want their Siamese twins separated and understand and accept the risks -- but what if you have had to force the whole thing on them in the first place? A key Problem in Siamese twin decisions is that the parents themselves may no always agree on the separation, and it is common for them to feel somehow that the birth of Siamese twins is their fault, or to blame each other, doctors, society or God. The natural joy of birth has been replaced by deep grief for the loss of one or two perfectly normal children.
And there is another issue. The survivor of these Siamese twins would need huge care efforts. This would be unlikely in some cultures and parents may feel very angry at medical interference.
On balance, doctors should tread with great care when it is a human right and the responsibility for parents to make decisions on behalf of their children to refuse certain medical treatment.
