Chorionic villus sampling: risks and alternatives

• Chorionic villus sampling allows the study of genetic, chromosomal and other malformations with high accuracy.
• Chorionic villus biopsy is indicated when there is a high risk for chromosomopathies, i.e. after screening in the first trimester of pregnancy (≥1/250).
• After chorionic villus sampling, home rest for the first 24 hours and reduced physical activity during the first week are recommended.

Chorionic villus sampling or chorion biopsy is a prenatal diagnostic test performed to detect abnormalities in the chromosomes of the foetus by analysing the genetic make-up of the chorionic villi, cells that protrude from the amniotic sac.

This invasive test is performed between 11 and 12 weeks of gestation, although in some cases it is also performed at 13 weeks. This test should never be performed before 10 weeks, as it may cause shortening of the foetus' limbs.

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Like other invasive tests, such as amniocentesis, chorionic villus sampling is only performed on mothers who have a family history of specific genetic problems or a specific risk factor, i.e. if the specialist detects that the baby may be at risk for a disorder: Down syndrome; Tay-Sachs disease; sickle cell anaemia; cystic fibrosis, among others.

Chorionic villus biopsy cannot detect neural tube defects such as spina bifida.

Chorionic villus sampling results may be available 2-3 days after the puncture. When inconclusive results are given, approximately 2%, amniocentesis will be recommended.

As you may already know, before this type of invasive prenatal test is put into practice, specialists resort to non-invasive prenatal screening tests, such as the Prenatal Harmony Test or the double test PrenatalSafe® Karyo Plus + GeneSafe® Complete. We explain them in detail in the alternatives section.

One of the goals of non-invasive prenatal testing is to be able to provide early reassurance to parents when the result is normal and, if a chromosomal abnormality is diagnosed, to provide early counselling to enable them to opt for an earlier and safer termination for the mother. 

First trimester prenatal diagnosis has made it possible to enter the second trimester with the issue of "chromosomal diagnosis" virtually resolved.

We invite you to continue reading to find out all the details about this issue, the chorionic villus sampling, as well as the non-invasive prenatal tests, a highly recommended option to ensure the real need to resort to risky pregnancy tests.

Although chorionic villus sampling is a safe test performed under strict control, there are potential risks that can endanger the pregnancy, as well as the mother's health and the proper development of the foetus. Below, we explain the complications associated with this technique.

First of all, this procedure is not routinely offered to all pregnant women, because it has a higher rate of gestational loss than amniocentesis, with a 1-3% of infant death, although the skill and experience of the doctor performing the test must also be taken into account.

The risk of miscarriage following invasive prenatal testing is always higher in the first trimester than in the second.

There are also studies indicating that a chorionic villus sampling performed before the 10th week of pregnancy may lead to limb defects in the baby, such as missing fingers or toes, as well as shortening of the limbs.

There is a 1% chance of obtaining a false positive result, called closed placental mosaicism, in which some of the placental cells tested contain abnormal chromosomes, but the foetus is normal. Therefore, if the chorion biopsy detects mosaicism, amniocentesis is recommended to determine whether the baby is actually affected.

Other common complications following chorionic villus sampling include the following:

• Vaginal bleeding, if performed transcervically.
• Abdominal pain at the puncture site, if performed transabdominally.
• Chorioamnionitis: premature rupture of membranes, infection of amniotic fluid and membranes (1%).
• Perforation of organs near the puncture site.

Also, to prevent these risky situations from becoming more complicated. There are cases in which it is not recommended to carry out a chorion biopsy, such as the following:

• Women with AIDS (HIV), hepatitis B and hepatitis C with high viral load. In these cases, the test is contraindicated to avoid the significant risk of transmission of the virus to the baby during the invasive procedure.
• Women with isoimmunisation. These are cases where there is feto-maternal blood incompatibility. This is a condition that develops when a pregnant woman has Rh-negative blood and the baby she is carrying has Rh-positive blood.

Want to make sure if you need to undergo a chorionic villus sampling? You can buy your voucher for any of our non-invasive prenatal tests by clicking on the image below:

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If you have any questions about how to purchase the test through Operarme, or you need to clarify the different options we have at your disposal, do not hesitate to contact our patient service department by filling out the contact form or by calling at +34 91 141 33 56.

Below, we explain all the details about each of the prenatal tests that you can find through Operarme, you will learn about the type of analysis of each test, as well as its particularities in the case of each pregnancy.

Non-invasive prenatal tests are screening tests. These tests help to find out if your baby is at high risk of having a genetic condition that affects his or her health.

In addition, this type of analysis can confirm the need for an invasive diagnostic test to determine the genetic condition or birth defect that specifically affects your child.

These prenatal tests pose no risk to you or your baby, as they only require a small sample of maternal blood, just like a routine blood test.

Non-invasive tests include the following:

Harmony Basic Prenatal Test

The Harmony Basic Non-Invasive Prenatal Test is indicated for pregnant women at least 10 weeks gestation, with a single or twin pregnancy, including pregnancies through egg donation (IVF).

This test evaluates the risk of trisomy 21, 18 and 13, i.e. Down's syndrome, Edwards' syndrome and Patau's syndrome, and anomalies in the X and Y chromosomes (Aneuploidies), as well as being able to determine foetal sex.

You will receive the complete results within 5-7 working days. Furthermore, it is not necessary to carry out the test on an empty stomach.

The results of screening tests can help you decide whether you want to have a diagnostic test.

Harmony Medium Prenatal Test

The Harmony Medium non-invasive prenatal test is a prenatal screening, which allows to know the health of the baby with only 10 weeks of pregnancy.

This test is indicated for mothers with a high risk of aneuploidy, whether due to a suspected aneuploidy in the ultrasound, a previous history of trisomy or another risk factor.

This test assesses the risk of trisomy 21, 18 and 13, i.e. Down's syndrome, Edwards' syndrome and Patau's syndrome, and abnormalities in the X and Y chromosomes (Aneuploidy), as well as being able to determine foetal sex (except in multiple pregnancies of only males).

Harmony Extended Prenatal Test

The non-invasive Harmony Extended Prenatal Test is a prenatal screening test, which will allow you to know the health of your baby at only 10 weeks of pregnancy.

This test evaluates the risk of trisomy 21, 18 and 13, anomalies in the X and Y chromosomes (Aneuploidies), and detects the probability of the 22q11.2 deletion known as DiGeorge syndrome. It is also able to determine foetal sex.

In the case of pregnancies with two foetuses or twins, only chromosomes 21, 18 and 13 will be analysed, i.e. sex aneuploidies will not be detected, nor will the 22q11.2 deletion be detected, and the foetal sex will be reported, as long as one of the babies is a boy, or both babies are girls.

The purpose of a free foetal DNA test is especially useful when confirming or detecting a chromosomal abnormality in the foetus, among other reasons, because it is a non-invasive technique, as well as for its effectiveness and reliability of > 99%. 

In this way, non-invasive prenatal testing helps to decide whether or not an invasive diagnostic test, such as chorionic villus sampling or amniocentesis, is necessary.

If you are interested in having any of these non-invasive prenatal tests, to be sure of the real need to resort to an invasive technique, such as amniocentesis. Or simply, to continue with a totally calm and safe pregnancy.

You can buy your non-invasive prenatal test voucher immediately and very easily by filling in our contact form, calling at +34 91 141 33 56 or clicking on the image below:

Do you need a Harmony Prenatal Test?

Buy your medical voucher easily under Operarme's guarantees and select your nearest laboratory.

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