Skip to Main Content

++

INTRODUCTION

++

Definitions

  1. Chorionic villus sampling (CVS): an invasive procedure performed for first-trimester prenatal diagnosis. CVS is typically performed between 70 and 91 days after the LMP. In the procedure, tissue is withdrawn from the villi (vascular fingers) of the chorion, a part of the placenta, and examined.

  2. Chorion frondosum: the cellular, outermost extraembryonic membrane, composed of trophoblastic cells, and develops villi, and forms the fetal component of the placenta.

  3. Fluorescent in situ hybridization (FISH): rapid method of assessing targeted chromosomal abnormalities such as trisomy 21, 18, or 13.

  4. First-trimester screening: a method of screening for chromosomal abnormalities in the first trimester using two biochemical tests, PAPP-A and hCG as well as sonographic nuchal translucency measurement.

++

Sonographically guided chorionic villus sampling (CVS) has been available in the United States since the early 1980s and has offered couples at genetic risk an early and rapid prenatal diagnosis.1 The procedure, which can be performed as early as 10 weeks of menstrual age, provides preliminary cytogenetic results within 48 hours and final culture results within 7 days. In contrast, genetic amniocentesis is not routinely performed until approximately 16 weeks of menstrual age with an additional 7 to 10 days required to culture the amniotic fluid cells. Fluorescent in situ hybridization (FISH) can be used for both of these techniques. Thus, the pregnancy is nearly half completed before a definitive diagnosis can be established with amniocentesis. If a significant fetal abnormality is identified, the prospective parents must make a difficult choice of whether to continue or terminate the pregnancy. Postponing this decision until the mid-trimester is extremely difficult because fetal movement has been perceived and significant bonding between the parent and fetus has occurred. In addition, the pregnancy is public knowledge, thereby precluding an element of privacy in decision making. If termination is chosen, maternal risks are greater than in the first trimester, with maternal mortality being up to 5 times higher.2

++

Despite the advantages of CVS, the procedure has struggled to become universally accepted. This has been due predominantly to a perception that the sampling and laboratory procedures are more complex than amniocentesis. In addition, there have been concerns that the procedure may induce fetal limb defects. Recently, however, enthusiasm for CVS has been renewed. First, contemporaneous studies have demonstrated the accuracy of the laboratory results, the reliability of the sampling, and the safety of the procedure if performed after 10 weeks of gestation by experienced operators. Second, studies have established the superior safety to CVS over first trimester amniocentesis.3,4, and 5 Additionally, over the last decade, the complication rates of CVS and mid-trimester amniocentesis are comparable due to the reduction of CVS problems.6 Third, the recent success of first trimester screening for fetal chromosomal abnormalities provides an impetus for a first trimester diagnostic procedure for fetal karyotype.7

++

CONCEPTS AND INDICATIONS FOR CHORIONIC VILLUS SAMPLING

++

For ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.

Ok

About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.