Chorionic villus sampling (trophoblast biopsy) is an invasive prenatal test performed in early pregnancy. What is chorionic villus sampling and what are the indications for this test? What defects of the fetus can be detected by chorionic villus sampling and is it safe? Is this test better than amniocentesis? These are just some of the questions pregnant women ask themselves about chorionic villus sampling. It is worth knowing the answer to them.

Chorionic villus samplingotherwise referred to as trophoblast biopsy or abbreviation - CVS (from the English name chorionic villus sampling), although the first term is by far the most common.

This test belongs to the so-called invasive prenatal tests - invasive, i.e. those during which the material for the test is collected through surgery, so there is a certain risk of complications associated with it.

Chorionic villus sampling is reimbursed by the National He alth Fund when there are indications for this test, and the referral (and the test itself) is performed by a doctor who has a contract with the National He alth Fund.

Chorionic villus sampling is performed in early pregnancy - between 10 and 14 weeks.

What fetal defects can be detected by chorionic villus sampling?

The chorion (or chorion) is the outer fetal membrane made of ectoderm, which covers the remaining fetal membranes (including the amnion) and the embryo, and over time transforms into the placenta. The chorion is made of the same tissues as the fetus, therefore chorionic villus sampling allows obtaining the genetic material of the fetus.

By examining the chorion, you can determine if the fetus is not burdened with genetic diseases. Chorionic villus sampling allows you to detect (or exclude) gene mutations, and the karyotype test allows you to detect chromosomal aberrations, e.g. trisomy (thus assessing whether the fetus has two or three chromosomes). With the help of chorionic villus sampling, it is possible to detect diseases and defects such as:

  • cystic fibrosis
  • Duchenne muscular dystrophy (muscle wasting)
  • sickle cell anemia
  • Down syndrome
  • Edwards syndrome
  • Patau band
  • Turner syndrome
  • Tay-Sachs team
  • hemophilia
  • alkaptonuria

It is worth remembering, however, that the study is -in order to detect a specific disease - it also requires a thorough medical history and other fetal test results ordered by the doctor - all because the sample is tested for a specific disease.

What are the indications for chorionic villus sampling?

Chorionic villus sampling is recommended in specific cases.

Chorionic villus sampling is performed:

  • when the expectant mother is 35 years old or older, due to the increased risk of having a child with genetic defects, mainly Down's syndrome
  • when previous tests (ultrasound, blood tests or nuchal translucency assessment) indicate an increased risk of having a child with a genetic disease
  • when the disease has occurred in the family in the past or it is known that the parents are carriers.
  • when an older child has a genetic disease

What is chorionic villus sampling?

Chorionic villus sampling (trophoblast biopsy) involves the collection of a fragment of the chorion (outer fetal membrane) under ultrasound guidance.

You should come for the procedure with a referral and with full medical documentation and test results. The most important of these is the mother's blood type test - if the Rh factor is negative, the Coombs test, measured in the two weeks before the procedure, is also necessary.

The test takes several minutes.

The bladder must be emptied prior to the examination. The doctor then performs an ultrasound to determine the position of the placenta and the baby. Later, he retrieves a fragment of the chorion. There are two ways to get it (the decision depends on the position of the placenta and the baby):

  • Through the abdominal wall- this is what happens in most cases. The doctor inserts the needle through the abdominal wall and the uterine wall directly into the placenta (constantly monitoring its position with ultrasound). The needle sucks up a small amount of tissue, which is then secured and sent to the lab.
  • Through the cervix . The material is collected with the use of special, small forceps, which, thanks to ultrasound, the doctor can precisely direct to the right place. The material for the test is collected either with forceps or with a thin suction catheter.

The waiting time for the result depends on the disease for which the chorionic villus sampling is being performed. In some cases the result is known quickly (even within 1-3 days), in others, especially if the sample has to be subjected to a complex molecular test, the waiting time may be even several weeks

Is the chorionic villus sampling painful?

Chorionic villus sampling through the shellsabdominal is performed under slight local anesthesia. So you will be aware of what is happening, but you shouldn't feel any pain, just for a few days you may experience discomfort and a feeling similar to that of a delicate period.

If the material is collected through the cervix, you may experience similar discomfort as during cytology.

What happens after chorionic villus sampling?

Doctors warn that some women may experience slight spotting almost immediately after the examination, as well as pain in the abdomen, which is similar in intensity to those accompanying menstruation. Therefore, it is worth checking with your doctor in advance what you need to pay attention to and what may worry you.

You should not overexert yourself for a few days after the examination and you should avoid gymnastic exercises and sexual intercourse (especially if bleeding occurs). You should inform your doctor about any disturbing symptoms.

Chorionic villus sampling: what is the risk of miscarriage?

Trophoblast biopsy is associated with twice the risk of complications than amniocentesis. But that doesn't mean the risk is high. Complications after chorionic villus sampling include:

  • slight bleeding
  • immunization (in Rh negative women)
  • leakage of amniotic fluid
  • intrauterine infection
  • spontaneous miscarriage - according to various data, the risk ranges from 1 to 3 percent.

Contraindications for chorionic villus sampling

Contraindications to chorionic villus sampling are primarily a very early pregnancy (under 9 weeks). Moreover, this examination should not be performed before the 10th week of pregnancy due to the possibility of anatomical defects in the fetus.

Chorionic villus sampling is also not performed if anti-Rh antibodies are found in the mother's blood, and should also be performed with caution in HIV-infected women due to the possibility of transmitting the infection to the child.

Category:

Pregnant examinations