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Chorionic villus sampling (CVS) is a test that can find certain problems with your fetus. These include many diseases that run in families (genetic disorders) and chromosome defects. It is done during early pregnancy, most often between the 10th and 13th weeks.
are tiny finger-shaped growths found in the placenta. The chorionic villus cells have the same genetic material as the baby's cells. During CVS, a sample of the chorionic villus cells is taken. The sample is collected by putting a thin tube (catheter) through the vagina or by putting a long, thin needle through the belly. Ultrasound is used to guide the catheter or needle to the right spot.
CVS can find many genetic disorders, such as Tay-Sachs disease and hemophilia. It can also find chromosome defects, such as Down syndrome. CVS can't find neural tube defects.
CVS is done earlier in pregnancy than amniocentesis (usually done at 15 to 20 weeks). And the results of CVS are available sooner. This gives you more time to make decisions about your pregnancy or plan for the future.
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CVS may be done during your first trimester of pregnancy to find certain birth defects.
You may choose to have this test because:
You may be asked to drink a glass of fluid about an hour before the test. This is so your bladder will be full. A full bladder makes it easier to do the test.
You will be asked to sign a consent form that says you understand the risks of the test and agree to have it done.
Be sure to tell your doctor before the procedure if you are allergic to any medicines, such as numbing medicines (local anesthetics).
Talk to your doctor if you have any concerns about the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
CVS is usually done by a perinatologist. It may be done in the doctor's office or the hospital. An overnight stay in the hospital usually is not needed.
CVS may be done either through the belly (transabdominal) or through the cervix (transcervical). The choice may depend on the position of the fetus and the placenta.
You will lie on your back on an exam table with your belly bare.
Ultrasound will be used to help your doctor guide the needle to the placenta. Gel will be rubbed on your belly. An ultrasound device (transducer) will be moved over your belly. It gives off and picks up sound waves. The sound waves are sent to a computer to make a picture of your uterus, your baby, and the placenta on a screen. The doctor can also use ultrasound to check your baby's heart rate. For more information, see the topic Fetal Ultrasound.
Your skin where the needle will be put in is cleaned with alcohol and numbed with a medicine. Your doctor then puts a long, thin needle through your belly and uterus to the placenta. The needle is used to collect a sample of the chorionic villus cells.
After the sample is collected, the doctor may listen to your baby's heart and check your blood pressure, pulse, and breathing.
You will take off your clothes below the waist. You will have a paper or cloth covering around your waist. You will lie on your back on an exam table with your feet raised and supported by stirrups.
Your doctor will put a special tool with curved sides (speculum) into your vagina. The speculum gently spreads apart the vaginal walls. This lets the doctor see the inside of the vagina and the cervix. The cervix will be cleaned with a special soap.
Your doctor will use ultrasound to guide a thin tube (catheter) through your cervix to the placenta. Gel will be rubbed on your belly. An ultrasound device (transducer) will be moved over your belly. It gives off and picks up sound waves. The sound waves are sent to a computer to make a picture of your uterus, your baby, and the placenta. The doctor can also use ultrasound to check your baby's heart rate. For more information, see the topic Fetal Ultrasound.
When the catheter is in the right place, a sample of chorionic villus cells will be collected.
You will feel a short, sharp sting from the needle used to give the numbing medicine. There is usually no pain when the collecting needle is put in the belly. You may have some cramping when the needle is in your uterus.
Most women do not find this procedure painful. It may feel like having a Pap test or pelvic exam. You may have some cramping when the catheter is put through your cervix.
CVS may cause cramping, leakage of amniotic fluid, and vaginal spotting. These will go away in 1 to 2 days. If you had the belly procedure, you may feel some soreness where the needle was put in.
CVS also increases the risk of:
There is a very small chance that CVS could cause bleeding that could let your blood mix with your baby's blood. If you have Rh-negative blood, you will be given the Rh immunoglobulin vaccine (such as RhoGAM). This can prevent Rh sensitization, which could harm your baby if he or she has Rh-positive blood.
It is normal to have mild cramping and vaginal spotting and to leak a little amniotic fluid for the first day or two after the procedure.
Call your doctor right away if you have:
Chorionic villus sampling (CVS)
is a test that can find certain problems with your fetus. It is done during early pregnancy, most often between the 10th and 13th weeks.
The genetic material (chromosomes) of the cell sample is looked at carefully. Normally there are 46 chromosomes in each cell, arranged in 23 pairs. The number and arrangement of the chromosomes in the sample can show if your baby has a genetic disease. Chromosomes also show the sex of your baby.
It may take 1 to 2 weeks to get CVS results.
No abnormalities are found in the genetic material of the chorionic villus cells.
Abnormalities are found in the genetic material of the chorionic villus cells.
CVS can find certain problems, but normal results don't guarantee that your baby will be healthy.
In rare cases, the chorionic villus cells may have abnormal genetic material even though the baby's cells are normal. This is called a false-positive result. An abnormal test result may need to be confirmed by amniocentesis.
Your doctor will talk with you about anything that might keep you from having the test or that may change the test results.
Akolekar R, et al. (2015). Procedure-related risk of miscarriage following amniocentesis and chorionic villus sampling: a systematic review and meta-analysis. Ultrasound in Obstetrics and Gynecology, 45(1): 16-26. DOI: 10.1002/uog.14636. Accessed April 5, 2017.
Other Works Consulted
American College of Obstetricians and Gynecologists (2007, reaffirmed 2008). Screening for fetal chromosomal abnormalities. ACOG Practice Bulletin No. 77. Obstetrics and Gynecology, 109(1): 217-227.
Cunningham FG, et al. (2010). Prenatal diagnosis and fetal therapy. In Williams Obstetrics, 23rd ed., pp. 287-311. New York: McGraw-Hill Medical.
Wapner RJ, et al. (2009). Prenatal diagnosis of congenital disorders. In RK Creasy et al., eds., Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice, 6th ed., pp. 221-274. Philadelphia: Saunders Elsevier.
ByHealthwise StaffPrimary Medical ReviewerSarah A. Marshall, MD - Family MedicineAdam Husney, MD - Family MedicineKathleen Romito, MD - Family MedicineElizabeth T. Russo, MD - Internal MedicineKirtly Jones, MD - Obstetrics and Gynecology, Reproductive Endocrinology
Current as ofNovember 21, 2017
Current as of:
November 21, 2017
Sarah A. Marshall, MD - Family Medicine
& Adam Husney, MD - Family Medicine & Kathleen Romito, MD - Family Medicine & Elizabeth T. Russo, MD - Internal Medicine & Kirtly Jones, MD - Obstetrics and Gynecology, Reproductive Endocrinology
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