In conventional medicine the aim of diagnosis is to enable the patient to be treated most effectively, and if diagnosis should turn out to be one for which no effective treatment is available, then the aim is to ameliorate the patient's condition as far as this is possible.
But the object of prenatal diagnosis of genetic defects is exactly the opposite. The aim is to find out whether the foetus has some defined abnormality and, if so, to abort the foetus.
It is not therefore surprising that the introduction and increasing application of prenatal diagnosis with its corollary, the abortion of foetuses with a defined abnormality, should have generated a considerable amount of discussion and argument.
In general the introduction of prenatal diagnosis and selective abortion into medicine has raised a variety of ethical and biological questions which can be expected to have important social implications. But before considering these questions further it is obviously desirable to examine the general scope of the procedure and, in particular, the types of situation to which it can be applied.