Sharing information today to save the lives of tomorrow.
Isoimmunization: An Intro to Antibodies in Pregnancy
Empowering women to be partners in their prenatal care.
Sharing information today to save the lives of tomorrow.
Sharing information today to save the lives of tomorrow.
Cell Free Fetal DNA Testing
cffDNA Testing
In the US the test is called Sequenome Sensigene (for anti-D moms only). You also have the option of sending blood to the UK or Netherlands to test for Kell, C, c, E, and e. cffDNA testing is now being done in Australia as well as some parts of Canada.
What is it?
cffDNA is a blood test where they draw mom's blood and separate out tiny bits of baby's DNA. This lets them determine baby's antigen status.
Who should be tested?
Moms who are unable to test dad's phenotype would benefit from the cffDNA test. If dad is heterozygous (Ee or Kk), the cffDNA test would help as well.
When is it done?
Around 12-16 weeks of pregnancy. If done earlier, it may need to be repeated later when there's more of baby's cells in mom's system.
Canada: Kell >28 weeks. 16 weeks for D, C, c, E, e.
UK: Kell >20 weeks. 16 weeks for D, C, c, E, e.
Netherlands: Kell 14 weeks. D, C, c, E, e >9 weeks, but prefer 12 weeks or older.
Why is it done?
To determine baby's antigen status and to find out if baby is at risk of being attacked by mom's antibodies. If baby is negative for the antigen that matches mom's antibody, then baby will be safe.
How often is it done?
Usually just once unless the test was done too early, then it may need redone again after 14 weeks. They will also repeat a negative test result at 20 weeks just to be sure.
How is it done?
Print out the instructions and the request form Bring both forms to your doctors office and laboratory.
Instructions:https://www.sanquin.org/binaries/content/assets/en/products-services/diagnostic-services/diagnostic/instructions-for-non-invasive-fetal-dna-testing.pdf
Request Form: https://www.sanquin.org/binaries/content/assets/en/products-services/diagnostic-services/diagnostic/request-form-2a-non-invasive-fetal-genotyping
If the above links stop working, try the landing page at https://www.sanquin.org/products-and-services/diagnostics/non-invasive-fetal-blood-group-genotyping
What do the results mean?
If baby is positive, then he is at risk of being attacked by the antibodies and developing Hemolytic Disease of the Fetus and Newborn. If he is negative, then baby is safe.
When should I get additional monitoring?
What risks are there?
The risks with the cffDNA test are the same with any blood draw.
What are the benefits?
If baby is negative for the antigen that matches mom's antibody, then baby will be safe. Benefits include decreased cost (no MCA ultrasounds needed, no weekly appointments, travel, etc), more free time (less going to appointments), and less stress for the family. There is also no risk of loss, hemorrhage, or an increase in titers unlike with an amniocentesis or chorionic villus sampling.
Additional Info
If you are not in a country that does cffDNA testing for the antigens matching your antibody, blood is shipped to the Netherlands or the UK. See the Sanquin link below for information on sending blood to the Netherlands. Current cost (2019) is 800 Euros for the testing. Insurance may cover it if you and your doctor write letters explaining the disease and potential costs (ie each Level II Ultrasound costs $900 at 1 per week for 20 weeks that's $18,000 the insurance company can save if baby is tested and found to be negative).
If you have ANY antibody that is not anti-D, and your blood type is A-, AB-, B-, or O-, GET YOUR RHOGAM! If you have anti-D and anti-C together, get it checked to be sure that it is not really anti-G. If you have anti-D and anti-C, you may still need Rhogam if it is really anti-G.
How to submit blood for the cffDNA test
Print out the instructions and the request form Bring both forms to your doctors office and laboratory.
Instructions:https://www.sanquin.org/binaries/content/assets/en/products-services/diagnostic-services/diagnostic/instructions-for-non-invasive-fetal-dna-testing.pdf
Request Form: https://www.sanquin.org/binaries/content/assets/en/products-services/diagnostic-services/diagnostic/sanquin-international-immunohematology-diagnostics-request-form-non-invasive-fetal-genotyping-2a-juni-2017.pdf
Links
Article about the usefulness of cffDNA: https://losinglucyandfindinghope.files.wordpress.com/2016/12/scheffer_et_al-2011-bjog__an_international_journal_of_obstetrics__gynaecology.pdf
USA Sensigene RhD test website: https://www.sequenom.com/tests/reproductive-health/sensigene-rhd
Australian Red Cross Non-Invasive Prenatal Analysis (NIPA) for RhD website: https://transfusion.com.au/node/809
Neatherlands Sanquin website: https://www.sanquin.org/products-and-services/diagnostics/non-invasive-fetal-blood-group-genotyping
UK Testing for those in the NHS system: https://ibgrl.blood.co.uk/services/molecular-diagnostics/fetal-genotyping-diagnostic-test/
Canadian Blood Service: https://blood.ca/en/laboratory-services/fetal-genotyping-maternal-plasma-0