blood samples and swab DNA testing comparisonsThe two most popular methods for collecting DNA in labs are blood samples and mouth swabs.  The DNA testing results from extracting DNA-rich cells by swabs or blood samples are exactly the same, only there are differences in how the two samples are processed. Both have their advantages and disadvantages depending on your preference. Neither has been proven to be more accurate than the other, so it ultimately depends on your preference or the lab’s ability to provide.  The convenience and comfort of a buccal/mouth swab makes it the clear favorite for DNA paternity testing! Let’s explore how these two methods work.

How Swabs and Blood Samples Work
Persons seeking DNA samples for paternity cases or immigration cases usually follow the normal procedures in DNA testing centers around the country. DNA collected from a blood sample is exactly the same as DNA collected from your cheeks. So when blood is analyzed, the results are going to be as accurate as the DNA collected from your cheeks. There are actually several different methods for collecting DNA from your mouth;

  1. Dry procedures – These require the insertion of swabs that scrape tissue from your gums and cheeks. They can potentially also contain bacteria from your teeth.
  2. Wet procedures – This usually involves swishing a liquid around in your mouth and spitting the specimen into a collecting device. During this process, bacteria can also be released into your sample.
  3. Noninvasive procedure – With some procedures, you spit out the collecting solution and another is added to eliminate bacteria and help preserve the integrity of the sample.

Depending on which procedure is used at the DNA testing facility, a collection specialist verifies the person’s identity, gets a signed consent form, swabs the inside of the patient’s cheek, and then safely packs the DNA specimen into its safe storage. The process of collecting blood works basically the same, but isn’t quite as easy – a needle is inserted to draw your blood. Some patients are squeamish with needles, so there is always that initial testing apprehension. The process for both swab samples and blood samples is relatively straightforward, but there are indeed pros and cons for each that are discussed below:

Pros and Cons for Swab Samples
Swab collections have a number of advantages:

  • No needle is used, no puncture of the skin is necessary
  • It’s a quick, non-invasive procedure, with no pain involved
  • The DNA collected is good indefinitely after collection if stored properly
  • Scientists prefer the easier extraction process from a testing point of view
  • Patients usually are more relaxed and less stressed about the DNA collection process
  • They’re relatively affordable to collect

On the other side, the main cons ascribed to swabs are:

  • Bacteria can attack the cells containing DNA if not dried and stored
  • Since the cells are not visible, there is no way to visually verify DNA is present

Pros and Cons for Blood Samples
Taking blood samples for DNA testing do have a few pros of their own, including:

  • Clean blood in proper tubes minimizes chances of contamination
  • Fast and quick procedure
  • Blood samples are visible

However, in some rare instances, if a person has recently had a blood transfusion before a sampling is drawn, the results could show two separate DNA samples. Clearly, though, the chances of this happening are on the rare and unexpected side. Blood samples do have cons for patients seeking this type of DNA test:

  • Needles puncture the skin – patients will feel some degree of pain
  • Multiple attempts may be required to insert the needle into smaller, thinner blood veins
  • Possible screaming and crying if children are required to get a DNA blood sample
  • Blood samples are fast to collect, though not as quick as swab samples

Test Reliability
Swab tests are highly reliable because of the source of its DNA. Some people believe the buccal epithelial cells are the only source of DNA. But, research studies show differently. And in fact, a study by Thiede and others in Bone Marrow Transplantation shows up to 74% comes from white blood cells. No matter which method is used though, a DNA sample from your mouth is just as accurate as one from your blood sample when processed by an experience testing laboratory.

Which Would You Use?
Both of these tests have their advantages and disadvantages. The bottom line is that you get highly reliable paternity test results from both. From a practical perspective, it does not matter which procedure you opt for. After learning a little more about both processes, you might now have a clear idea of which one makes the most sense for you.