Advance in invasive prenatal diagnosis and fetal therapy

Invasive proeedures for prenata! diagnosis have undergone rapid evolution with the availability of inereasingly sophistieated ultrasonographic modalities. A\though second trimester amniocentesis fol1owed by eytogenetic or biochemical analysis of euHured amnioıic fluid cells brought prenata! diagnosis into the mainstı'cam of pregnaney management, it has been overshadowed in rccent years by advanees in gampling and laboratOl'y methods. Thus, chorlonic villi biopsy has moved prenatal deıection from thc second to the fırst trimester, whereas cxperiencc is been aecumuIating with early amniocentesis (bcfore 15 weeks of gestation). Fetal blood sampling and fetal biopsy have given access to specialised tissues for rapid karyotyping, biochemica! or histological analysis. In the !aboratory the development of recombinant DNA technology, and in partieular tests based on polymerase ehain reaction (peR), has revolutionised fetal diagnosis and carrier detection of single gene disorders, or diseases caused by expansion of simple DNA sequenee repeats, a new mutagenie mechanism. The fcasibiliıy of detecting chroınosomal aneuploidies using fluorescent in situ hybridisation (FISH) on interphase or metaphase cells has aıready significant clinical impacl. These methods can enhance the speed and accuracy of diagnosis. Once effective prenatal diagnostic procedures become estabHshed the same evoluationary step s in medical concepts for postnatal life can be expected for the fetlls with a correctable congenital defect or disorder. The ability to achieve early diagnosis is a significant steps towards the potential for fetal therapy. It provides time for counselling and to determine whether thenıpy is feasible or indeed appropriate, Fetal therapy includes transplacental drug provision, minimally invasive procedures, manipulation of amniotic fluid, transfusion of blood products, transplantation of progenitor hematopoietic cells, drainage and slıunting procedures, and open human fetal surgery. Although most fetal treatment is stiıı experimentat, the siage is now set for intrauterine fetal therapy; the final domain and next excjtjng frontier for perinatologİs[s.

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