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Chorionic Villus Sampling

Chorionic villus sampling (CVS) is a pregnancy test to check if your baby has a genetic or biochemical condition, such as Down's syndrome, Edwards' syndrome or Patau's syndrome.

is chorionic villus sampling

Chorionic villus sampling is a prenatal test usually carried out between the 11th and 14th weeks of pregnancy. A small sample of the placenta that contains some of your baby’s cells and genetic information (DNA) is taken for genetic diagnosis.

CVS is a non-routine and invasive test that is only offered if there's a high chance your baby could have a genetic or chromosomal condition. We offer a CVS if:

  • your screening-test or ultrasound scan result suggests your baby has a higher chance for Down’s syndrome or Edwards’ syndrome and Patau’s syndrome
  • you had a previous pregnancy affected by a genetic condition
  • you have a family history of a genetic condition, such as sickle cell disease, thalassaemia, cystic fibrosis or muscular dystrophy.

It is your decision whether to have a CVS or not. There is no cure for most of the conditions found by CVS. Your healthcare professional will help you to understand the implications of the test, to consider your options carefully and make a decision that is right for you, and support you in your decision.

What does a CVS test tell you?

A chorionic villus sampling test tells you if your baby has a chromosomal condition, such as Down’s syndrome, as well as other genetic conditions, such as cystic fibrosis. Unlike amniocentesis (another prenatal test), CVS does not test for neural tube defects, such as spina bifida. A follow-up blood test at 16 to 18 weeks of pregnancy can be performed to screen for neural tube defects.

A CVS can count the number of chromosomes and check their structure. If you are having a CVS to test for a specific genetic condition, the cells in the sample are tested for this.

Your first test results should be available within three working days. They tell you if a chromosomal condition has been found. These include Down's syndrome, Edwards' syndrome or Patau's syndrome.

Rarer condition testing can take two to three weeks or more for the results to come back. You can get the results over the phone or face-to-face and you'll also receive written confirmation of the results.

This test can provide you with valuable information about your baby's health. You need to be prepared for the results as well as understand the risks.

How do they test chorionic villus sampling?

Chorionic villus sampling involves removing a small sample of cells from your placenta. This can be done using one of two methods:

  • transabdominal CVS – most commonly performed. A needle is inserted through your stomach.
  • transcervical CVS – small instruments are passed through your cervix (the neck of your womb).

The test takes about 10 minutes. The sample is then sent off to the laboratory for testing.

How accurate is a CVS test?

CVS gives a definitive result in 99% of women who have the test. However, it is not always possible to get a conclusive result that establishes with certainty if your baby will have the condition the test is looking for. This might be due to the collection of too small a sample of cells or that there's a change in the structure of the chromosomes in the placenta and not in the baby. If this happens you will be offered a second procedure. This could be a repeat CVS or an alternative test called amniocentesis where a sample of amniotic fluid is taken from your womb.

You should also be aware that there is an additional risk of miscarriage following CVS or amniocentesis. When performed by a skilled surgeon this is likely to be below 0.5%. There is also a 1% additional risk of miscarriage for twin pregnancy following a CVS.

What is the function of chorionic villi?

Chorionic villi are small finger-like projections of placenta tissue that contain the same genetic material as the foetus. Tiny blood vessels in the chorionic villi allow the transfer of oxygen and nutrients from the mother's blood to the foetus. Carbon dioxide and waste products from the foetus also pass through the chorionic villi back into the mother's blood.

What is the recovery process after a chorionic villus sampling?

After a chorionic villus sampling, you will be monitored for up to an hour to check for any side effects, such as heavy bleeding. You can then go home. It’s advisable to arrange for someone to drive you home and to avoid any strenuous activity for the rest of the day.

You may have some cramping and light vaginal bleeding for a few hours after your CVS. This is normal. You can take paracetamol for any discomfort.

What is the cost of a chorionic villus sampling?

The cost of a CVS will depend on your Ramsay hospital of choice.

You will receive a formal quotation price after your consultation with one of our expert surgeons. This formal quote for your CVS will be valid for 60 days.

Chorionic villus sampling is covered by most medical insurance policies if your doctor recommends it. We advise that you check with and obtain written confirmation from your insurance provider prior to having this test.

Chorionic Villus Sampling at Ramsay Health Care

Chorionic villus sampling is safely and regularly performed at Ramsay Health Care by highly experienced and skilled doctors.

When you come to Ramsay Health Care for your CVS, you will have the opportunity to discuss in detail why you are being offered the test and the implications of the test results. We offer full support when you receive the results and in making further decisions regarding your pregnancy.

All of our hospitals follow strict protocols to minimise the risk of infection for visitors and staff alike, including Covid-19.  

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