Medical Genetics In general, risks will depend on (1 the experience of the obstetrician performing the procedure; (2 clinical characteristics of a particular case(e. g presence or a bsence of biochemical markers of fetal abnormality) (3 the quality of the high-resolution ultrasound utilised
Medical Genetics In general, risks will depend on (1) the experience of the obstetrician performing the procedure; (2) clinical characteristics of a particular case (e.g., presence or absence of biochemical markers of fetal abnormality); (3) the quality of the high-resolution ultrasound utilised
Medical Genetics Early amniocentesis With development of higher resolution ultrasound equipment, some centres have begun offering amniocentesis before 15 weeks gestation usually between 10 and 14 weeks. The majority of procedures have been performed during the 13th and 14th weeks of gestation
Medical Genetics Early amniocentesis With development of higher resolution ultrasound equipment, some centres have begun offering amniocentesis before 15 weeks gestation, usually between 10 and 14 weeks. The majority of procedures have been performed during the 13th and 14th weeks of gestation
Medical Genetics There is evidence that early amniocentesis is associated with a higher fetal loss rate and a more frequent occurrence of certain congenital abnormalities
Medical Genetics There is evidence that early amniocentesis is associated with a higher fetal loss rate and a more frequent occurrence of certain congenital abnormalities
Medical Genetics B, Chorionic villus sampling Chorionic villus sampling(cvs) is the only tested method for first trimester fetal genetic diagnosis that is currently in clinical use and is usually performed between 9 and 11 weeks
Medical Genetics B. Chorionic villus sampling Chorionic villus sampling (CVS) is the only tested method for firsttrimester fetal genetic diagnosis that is currently in clinical use and is usually performed between 9 and 11 weeks
Medical Genetics The procedure involves the passing of a sampling instrument into the chorion(developing placenta). A good procedure yields from 10 to 25 mg of tissue which is adequate for cytogenetic, enzymatic or dNa analysis
Medical Genetics The procedure involves the passing of a sampling instrument into the chorion (developing placenta). A good procedure yields from 10 to 25 mg of tissue which is adequate for cytogenetic, enzymatic or DNA analysis