Dissection of fetal chorionic villus

Dissection of fetal chorionic villus material from maternal
decidua permits analysis of the fetal genotype. The main
indications for chorionic villus sampling include the diagnosis
of chromosomal disorders from familial translocations and an
increasing number of single gene disorders amenable to
diagnosis by biochemical or DNA analysis. The advantage of
this method of testing is the earlier timing of the procedure,
which allows the result to be available by about 12 weeks’
gestation in many cases, with earlier termination of pregnancy,
if required. These advantages have led to an increased demand
for the procedure in preference to amniocentesis, particularly
when the risk of the disorder occurring is high. If prenatal
diagnosis is to be achieved in the first trimester it is essential to
identify high risk situations and counsel couples before
pregnancy so that appropriate arrangements can be made and,
when necessary, supplementary family studies organised.