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DNA testing whilst Pregnant: Amniocentesis, CVS and Non Invasive Testing

DNA testing whilst Pregnant: Amniocentesis, CVS and Non Invasive Testing

The risks of fetal DNA testing to establish the baby’s health or even paternity have been well documented and researched. It is important in some cases to be able to analyze samples of fetal DNA to determine how likely it is that the unborn baby might be suffering from any chromosomal abnormalities or congenital disorders. This will ensure that any complications in pregnancy are catered for and pre-empted. It will even help parents make certain important decisions.

There are several methods which can be used to determine whether or not the unborn baby is suffering from any condition such as Turner’s syndrome or Down’s syndrome. Obstetricians may in fact get the earliest indications from a simply ultrasound. If the ultrasound imaging shows certain characteristic signs of Down’s syndrome or a number of other abnormalities, they may suggest that the pregnant mother undergoes an invasive fetal DNA sampling method so as to confirm with a high degree of accuracy whether the fetus is in fact suffering from Down’s syndrome (invasive sampling methods include amniocentesis and chorionic villus sampling). Because of the risks associated with invasive sampling procedures and the fact that they cannot confirm with 100% accuracy whether or not the unborn baby will in fact suffer from the condition, some couples chose not to have any further tests as they are not willing to take on the risks. Other couples would rather go ahead and get a clearer picture of the situation. The same prenatal fetal sampling method used to determine fetal health, are also used to carry out a prenatal paternity testing.

The risks, in the worst case scenario, include miscarriage. All couples should carefully assess the benefits and the risks. Ultimately, if they will keep the baby or terminate the pregnancy should they find out that they will likely have a handicapped child is the main challenge faced. In some countries it is the norm to terminate pregnancies of handicapped fetuses which explains the extremely low incidence of handicapped children in Scandinavian countries.

Non Invasive Prenatal Sampling

It is possible to avoid all the risks entailed in prenatal tests like amniocentesis and chorionic villus sampling using non invasive prenatal testing. Non invasive prenatal testing is done using maternal blood samples which are collected using standard methods for blood sample collection. Due to the established fact that an expectant mother carries her baby’s DNA in her blood stream, this non invasive test is possible and yields very accurate results. Non invasive prenatal paternity testing using blood samples is in fact not offered by many leading companies and laboratories including easyDNA South Africa, International Biosciences and others. The accuracy of prenatal paternity testing with blood samples is around 99.9%. Maternal blood samples can also be used to determine whether or not the unborn baby suffers from Down’s syndrome. Scientists are still working on developing and refining analysis of blood samples to determine a wider spectrum of congenital and chromosomal defects, with the hope that in future pregnant mothers will not need to worry about the risks of amniocentesis and chorionic villus sampling – they will have a 100% safe alternative by carrying out non invasive prenatal testing. 

In-vitro Fertilization and Fetal Genetic Health

IVF has the advantage over natural conception in that it may be possible to diagnose chromosomal abnormalities before the fertilized egg is transferred into the uterus. If genetic analysis of the DNA within the fertilized egg shows any anomalies, the egg is destroyed. Very specialized laboratories offer this advanced type of pre-implantation testing.

Amniocentesis and CVS

Amniocentesis and chorionic villus sampling are two invasive DNA sampling techniques. The procedures are carried out at different times in pregnancy and the aim is to collect a sample of fetal DNA. It is by analysis of this sample in a laboratory that a more accurate confirmation can be derived of the fetus’s health and determines whether there are any of a range of genetic abnormalities that sometimes affect unborn babies. The results are then disclosed to the parents who might decide to terminate the pregnancy or simple embrace the new found knowledge to learn more about how to care for a child with special needs, seeking prenatal counseling and finding all the information to help them bring up a new member to their family.

Amniocentesis is carried out between 15 and 20 weeks of pregnancy. The procedure involves inserting a needle through the abdominal wall into the womb. The needle is used to withdraw a small volume of amniotic fluid. Amniotic fluid is rich in fetal DNA. The health care professional will need to apply some local anesthetic to the area where the needle will be inserted and carry out the procedure closely guided by an ultrasound.

Chorionic villus sampling is carried out earlier than amniocentesis. It is carried out between the 11th and 14th week of pregnancy. The procedure is not very different from amniocentesis and still requires an ultrasound to ensure insertion into the correct place inside the womb. CVS can be done by either inserting a needle through the abdomen or a catheter through the cervix.

There are many factors which determine whether or not you will need to have these tests carried out; you age while pregnant, your family genetic history and health history, the health history of the biological father, your previous pregnancies and whether these have resulted in any special needs children with chromosomal abnormalities and other factors which will be evaluated on a case by case basis.