Invasive Prenatal Diagnosis: Chorionic Villus Sampling

Chorionic villus sampling (CVS) is the method of choice for first trimester invasive prenatal diagnosis. In expert hands, it is nowadays considered as safe as amniocentesis and has the advantage of an earlier diagnosis. In this review, we des cribe the technique of the procedure, its indications and contra indications and the requirements concerning adequate training and optimum clinical practice. We also discuss issues concerning the safety of the procedure in singleton and multiple pregnancies, other complications and controversies, such as the association with limb reduction defects and pre-eclampsia, as well as diagnostic problems and dilemmas, such as maternal cell contamination and confined placental mosaicism. We also describe new and promising methods of non-invasive diagnosis, based on the isolation and analysis of fetal cells or cell-free fetal genetic material from the maternal circulation, that aim to replace the invasive methods of prenatal diagnosis in the future.