When dealing with genetic conditions, it’s important to have all the options available to you to protect your baby. At Love & Kindness, we are here to support you as you make all the decisions necessary for the health of your baby. Finding out that you are a carrier of a genetic condition that could be passed down can be terrifying news. There are two tests available to help determine the genetic health of your baby, CVS and Amniocentesis. In this blog, we will discuss the differences between these two tests and which option could be better for you.
Is Early Testing Necessary?
There is no short or easy answer to this question. Every situation is different and the need for genetic testing varies with each case. If your doctor feels like there are possible health complications that could be better assessed through testing, they might suggest one of these two testing procedures to prepare for the best outcome.
Early testing, such as CVS and Amniocentesis, can help reveal if a baby has a chromosomal condition, such as Down Syndrome, Neural Tube Defect, Cystic Fibrosis, or many other genetic conditions.
Also, for those over 35 years of age, the risk for chromosomal defects or conditions is much higher. Genetic testing can reveal if any chromosomal conditions are present.
The knowledge that these two tests provide will give you the opportunity to seek early counselling for obstetric management, earlier referrals to pediatric specialists, and a safer pathway to early pregnancy termination if results are abnormal.
Chorionic Villus Sampling (CVS) is a test that samples the chorionic villi from the placenta for testing. Chorionic villi are tiny tissues located in the placenta that contain the same genetic makeup of the fetus. CVS is typically done between weeks 11 & 14 of pregnancy, which is earlier than other tests, such as amniocentesis.
There are two different ways to sample the chorionic villi for testing – transcervical or transabdominal.
Transcervical – Transcervical chorionic villus sampling is done through the cervix. Your Doctor will open your vagina with a speculum, inserting a catheter to reach the placenta. Upon reaching the placenta, gentle suction will remove a tissue sample that can be tested.
Transabdominal – Using a long needle, your doctor will collect a sample of the placenta. Inserting the needle through your abdominal wall, the tissue will be drawn into a syringe and the needle will be removed.
Once the chorionic villi have been retrieved via transcervical or transabdominal sampling, tests can be performed. Your doctor should have the Chorionic Villi Sampling results within 2-3 weeks.
Amniocentesis is a test that involves removing amniotic fluid from the uterus for testing. The amniotic fluid contains fetal cells and various proteins that give us a better understanding of the fetus’ genetic makeup.
Amniocentesis testing is usually done between 15-20 weeks of pregnancy.
First, your doctor will perform an ultrasound to find the baby’s exact location in the uterus. The ultrasound will be used as a visual guide during the procedure. Next, using a long needle, amniotic fluid will be drawn up through the abdominal wall.
Your doctor should have the test results within 2-3 weeks after testing.
Risks with CVS & Amniocentesis
Now that we’ve discussed the process of both CVS and amniocentesis testing, it’s important to discuss the risks involved with each. When doing genetic testing through CVS and amniocentesis, the risks between the two are very similar.
Infection – In extremely rare cases, CVS testing might trigger a uterine infection.
Rh Sensitization – During CVS testing, some of the baby’s blood cells could enter the Surrogate’s bloodstream. If your Surrogate has Rh negative blood and she hasn’t developed antibodies, she will be given an injection of Rh immune globulin, a blood product, after chorionic villus sampling.
Miscarriage – The risk of miscarriage after chorionic villus sampling is 0.22 percent, higher than amniocentesis testing due to CVS testing being done earlier in pregnancy. For amniocentesis testing, the risk of miscarriage is lower – about 0.1 to 0.3 percent. In clinics and centers where CVS and amniocentesis testing is done regularly, the risk of miscarriage is extremely rare.
We hope that this information helps you to feel confident in your decision regarding genetic testing such as CVS and amniocentesis. As parents, you will want to do everything possible to protect the baby, but these genetic tests might not be necessary for you. Discuss with your clinic and your Surrogates’ OBGYN your concerns and questions to see if genetic testing is right for you and your baby.