Amniocentesis and Chorionic Villus Sampling Tests in Pregnancy

I have had both an amniocentesis and a chorionic villus sampling (CVS) done on different pregnancies. The process is mainly the same for both tests but a CVS is performed between 11 and 16 weeks and an amniocentesis is performed between 14 and 22 weeks normally. Both tests are used to determine if there are any fetal abnormalities and any genetic disorders.

The first time I encountered the CVS test was for my third pregnancy. I had been for a scan at 11 weeks to confirm my dates but the scanner found an anomaly and so I was referred to a specialist in pre-natal anomalies. I was given another ultrasound scan but was told I had to wait another week for a CVS test as the baby was too small. When I went back a week later, I was given another scan and it was confirmed that the baby was big enough for the test.

The test is performed by taking a sample of the placenta tissue by way of a long thin needle being inserted into the womb via the abdomen using an ultrasound scan as a guide. The needle did hurt a little as it entered my stomach but was not uncomfortable in any way. The whole test took about ten minutes and then I was shown to a room to recover from the test and so that the health professionals could keep an eye on me in case of emergencies. After the test it is normal to experience a small bit of cramping like period pains and there could also be a small bit of spotting. I experienced neither of these after I had the test. There is a slight risk of miscarriage with the test but the actual percentage depends greatly on the health professional performing the test as each individual has different percentages of miscarriages performing the CVS. The preliminary results are normally back within a couple of days and the conclusive results take about a week. Unfortunately for me, it was revealed that my baby had a genetic disorder of Trisomy 18 or Edwards Syndrome. As this is a very serious condition we decided to end the pregnancy.

As I had already had had a baby with a genetic disorder, when I became pregnant again, I was offered an amniocentesis as this carries a slightly lower risk of miscarriage and although the 12 week scan had showed no signs of abnormality, we decided to have the test. The amniocentesis is performed slightly later into the pregnancy than the CVS and instead takes a sample of the amniotic fluid instead of the placenta tissue. The test is still performed in the same way by passing a long thin needle into the womb by way of the stomach using an ultrasound as a guide. Again when the needle passes into the stomach it feels a bit uncomfortable but you should not be in a lot of pain. The test is performed quickly and was over and done in ten minutes. Again I had to stay in the hospital for a couple of hours after the test to ensure I wasn’t in a lot of pain. I did experience a few stomach cramps afterwards but other than that I felt fine. This time the results were favourable and no abnormalities were found in my baby. 

As well as showing if there any genetic abnormalities in the baby, both the CVS and the amniocentesis also confirms the sex of the baby. These tests are normally offered to women who are over the age of 35, where an early scan has shown abnormalities, where the results of a blood test show increased risks of genetic disorders or where there is a history of genetic disorders or abnormalities.