Molecular Diagnostics

Non-invasive fetal genotyping for mothers with antibodies

Molecular Diagnostics department offers fetal genotyping to provide molecular typing support for routine maternity and transfusion services both nationally and internationally.

The department offers a rapid, non-invasive, convenient and reliable service for prediction of fetal D, C, c, E and K status, using cell-free fetal DNA in maternal blood for women who have allo-antibodies.

Upon identification, mothers can then be informed and prepared for further careful monitoring during their pregnancy. The Molecular Diagnostics Department also identifies pregnant women who have antigen-negative fetuses and who therefore are not at danger from HDFN.

Ethics and benefits

Optimising antenatal care:

• clinicians can focus on women with an antigen positive fetus
• closely monitor antigen negative women with maternal allo-antibodies against fetal red cell surface antigens preventing Haemolytic Disease of the Fetus and New-born (HDFN)
• mothers with an antigen negative fetus can relax and enjoy their pregnancy with minimal monitoring

Overall it saves cost and time for those mothers who do not need:

• repeated clinic attendance
• doppler scans
• referrals for antibody quantification and titres
  
  

The blood group phenotype of a fetus can also be determined by analysis of DNA derived from fetal cells in amniotic fluid of chorionic villus (CV).

International customers

The fetal genotyping test is also available for non-UK customers under our Terms and Conditions contract by signing our referral form. Please contact our Business Development Manager Erika Rutherford for more information. 

Fetal RHD screening test

Only available to customers in the UK and Ireland

A cell-free fetal DNA screening service is also offered for determination of fetal D blood group in D negative pregnant women to guide the requirement for antenatal anti-D prophylaxis.

Molecular Diagnostics have optimised and automated the testing technology applied to pregnancies at risk of haemolytic disease of the fetus and new-born (HDFN) to enable sufficient high throughput testing to perform fetal RHD screening of all D negative pregnant women, who have not formed immune anti-D or anti-G³.

High-throughput non-invasive prenatal testing for fetal RHD genotype is recommended by the National Institute for Health and Care Excellence (NICE) as a cost-effective option to guide antenatal prophylaxis with anti-D immunoglobulin.

Ethics and benefits

Although anti-D Ig has been an exceptionally safe product, which should be strongly recommended to those women with a D-positive fetus, conditions such as prion disease and other as yet unknown factors should continue to make us ensure blood products are used only when needed.

Irrespective of the financial costs or benefits, it is unnecessary to continue administering a blood product to all D-negative women when a fetal RHD genotyping test, using maternal blood, could identify those women who do not need this product.

In addition, the availability of anti-D Ig, a human derived pooled product, is limited and requires deliberate sensitisation of volunteers. Both the difficulties of availability and the theoretical risks mean it should be used only when required.

We can also support you with the following information when you contact us:

• examples of maternity pathways led by either clinical or laboratory-based teams
• a calculation template to assess your cost (savings)
• question and answer document
• business plan support
  
  

Further support from our Business Development Manager is available, please contact:

Erika Rutherford
Mobile: 07808 906398
Email: erika.rutherford@nhsbt.nhs.uk

Red cell genotyping

In multi-transfused patients or DAT positive patients, the presence of transfused red cells or auto-antibodies can prevent determination of blood group phenotype by serological techniques. In these cases, analysis of genotype can be used to predict blood group phenotype.