Paternity Testing with Blood| Paternity Testing with Saliva

08 Jul 2017

Traditionally, the main source of DNA was blood and this idea has really stuck so that many still ask about paternity testing with blood; paternity testing with saliva sounds odd. Blood is now considered to be out-dated and saliva paternity tests have become the standard.

DNA and paternity testing

DNA is found throughout all nucleated cells in the body. Only cells containing a nucleus contain the necessary genetic material for a paternity test. Paternity testing with blood is thus accurate because blood contains white blood cells in large numbers and these cells are ideal for extracting DNA. Moreover, in the days when DNA testing was still evolving, scientists needed to work with very large numbers of cells whilst today it is possible to work with far smaller samples with equal success.

A saliva paternity test offers a very high success rate. This sample is collected by means of a simple mouth swab which is rubbed for ten seconds on the inside of the mouth. The rubbing inside the mouth causes exfoliated cheek cells to stick to the swabs. These cells are just as good as blood cells for a paternity test.

Paternity testing with blood: The two main blood samples

One can either submit blood stains which may have been collected from a wound onto a Kleenex or perhaps a bandage. These can simply be sent in a paper envelope. These samples will need forensic DNA testing and not only will there be an added cost, but in the case of blood stains there is a small chance of sample failure. However, the chances of a laboratory successfully extracting DNA from the sample is 75%.

The other option is to have a medical blood draw. This means making an appointment with a doctor or clinic, waiting rooms and queues and moreover, dealing with dread many people feel when having their vein punctured with a needle. Children may be particularly distressed by this procedure. The success rate with a medical blood draw is 95%.

Advantages of a saliva paternity test over a paternity test with blood

The main reason for choosing saliva is the ease and painlessness of collecting the sample, the costs and medical appointments saved and the very high success rate -95%- of this sample. Even court ordered paternity tests are done using saliva samples.

Blood can also be an issue if you need to send it by post for laboratory testing. The postal services are very weary of blood- is it pathogen free? Is it packed in the right leak-proof container cushioned with the right material?

A paternity test with blood has become discouraged for very valid reasons- there is no reason to opt for this sample when one can easily opt for a paternity test with saliva.