In plain words
Chorionic villus sampling, or CVS, is a diagnostic test that takes a small piece of the placenta to check the baby's chromosomes. It can be done through the belly or through the cervix, usually between 10 and 13 weeks. It is different from screening such as cell-free DNA, which estimates risk and does not give a final answer. CVS can find some chromosome differences and genetic conditions, but it carries a small risk of . A genetic counselor can explain the test before a mother decides. Some mothers choose it when screening results or age raise a question. The choice is personal.
The deeper version
CVS samples chorionic villi for , , or exome sequencing, with transabdominal or transcervical routes depending on placental position. Procedure-related pregnancy loss has been estimated at roughly 0.1 to 0.3 percent in recent series, with higher estimates in older studies (Akolekar and colleagues, Ultrasound in Obstetrics and Gynecology 2015). Earlier CVS, before about 10 weeks, was associated with limb reduction defects in some studies, which is why the procedure is timed at 10 to 13 weeks. ACOG Practice Bulletin No. 226 (2020) says diagnostic testing such as CVS or should be offered to all pregnant women, whatever their age or screening result. Diagnostic yield for chromosomal abnormality is high, while the detection of variants of uncertain significance remains a counseling challenge.
Where it comes up
- Pregnancy at 35 and olderPregnancy: Your Body
- Prenatal tests and ultrasounds: what each one isPregnancy: Your Body
- Termination for medical reasonsLoss and Complications
What mothers here say about chorionic villus sampling
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Sources
- Mujezinovic F, Alfirevic Z — Procedure-related complications of amniocentesis and chorionic villus sampling. Obstetrics and Gynecology 2007
- American College of Obstetricians and Gynecologists — Practice Bulletin No. 226: Screening for fetal chromosomal abnormalities, 2020