Fetal Screening

The Molecular Diagnostics laboratory is now under the management of the H&I Function. There is no change to the services we provide, this includes the contact details for the laboratory, sample referral process or reporting. The UKAS Extension to Scope to move Molecular Diagnostics activities from customer number 9765 (IBGRL) to 9239 (H&I) has been granted.

Fetal RHD screening test

(only available to customers in the UK and Ireland – a service-specific contract is required)

IBGRL Molecular Diagnostics is a UKAS accredited medical laboratory (number 9765). We offer fetal RHD screening service to prevent unnecessary administration of anti-D prophylaxis. The test predicts fetal RhD status with high accuracy from a sample of maternal blood and will improve care for RhD-negative women in the UK and the Republic of Ireland by reducing the need to administer a blood product to healthy pregnant women.

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

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.

For further information about the fetal RHD screening test, please read our brochure.

This is not a diagnostic test for fetal RhD status for women who have made anti-D (or-G). Please refer to the management of pregnant women with alloantibodies.

Information about the accuracy of non-invasive fetal genotyping (PDF 123KB)

Investigation	Notes	Samples required	Accompanying form	Turnaround times
Fetal RHD screening test	Requires contract	Minimum of 6mL EDTA blood	FRM5197 (PDF 111KB) FRM5197 guidance (PDF 159KB)	Within 10 business days

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 cost neutral 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 uncertainty of availability and the theoretical risks mean it should be used only when required.

The cost of the test is offset by:

Reduction in administration of anti-D Ig at 28 weeks
Reduction in administration of anti-D Ig for potentially sensitising events in pregnancy
Reduction in quantification and serology testing when the fetal D status is known (BSH guidelines for antenatal testing)
Decrease in associated requests for feto-maternal haemorrhage estimation

Documents and ordering leaflets & referral forms

Please note: This service is only available to NHS Trusts who have signed a specific contract with NHSBT.

If you need further information please contact:

Molecular Diagnostics
Tel: 0117 921 7572
Email: Molecular.Diagnostics@nhsbt.nhs.uk

Documents and forms

Christmas & New Year 2024:

Information regarding sample referral to Molecular Diagnostics (PDF 566KB) over the Christmas & New Year period.
Information about Molecular Diagnostics opening times and transport availability (PDF 493KB) over the Christmas & New Year period.

Ordering request forms and leaflets

Fetal RHD screen request form and patient information leaflets can be ordered using the distribution hub.

For specific information on ordering the fetal RHD screening request form and patient information leaflet, please see our Fetal RHD Screening guidance (PDF 371KB) document.

Demand printed labels

If you would like NHSBT to consider accepting samples from your hospital / Trust which have been labelled using a demand printed labelling system, please complete the application form below. The sample label requirements are specified on the form.

Complete the application form

Reporting results and turnaround times

The Molecular Diagnostics department aims to report 98% of samples within 10 business days of receiving the sample. Customers will be informed by email or phone in the unlikely event that a delay is anticipated.

UK laboratories

Summary of 2017/22 turnaround times achieve (PDF 352KB)

Reports are issued electronically via Sp-ICE in PDF format to NHS England hospitals. Other service users within the UK and Ireland can apply for Sp-ICE access or receive paper copies of the reports (for which an additional charge will apply).

If you do not currently have access to the Sp-ICE browser and wish to view these reports, please contact your local Transfusion Laboratory Manager (Sp-ICE primary contact) or e-mail ICE@nhsbt.nhs.uk for training and access

On exceptional occasions, if paper reports are required, these may be provided for an additional administration charge by prior approval and arrangement with NHSBT.

International laboratories

A paper copy of results will be sent to the clinician/address indicated in the contract.

Sample acquisition and logistics

The service is tailored to the needs of local maternity services. Samples can be taken from 11⁺² weeks gestation at a routine antenatal clinic appointment.

Maternal blood samples must reach the International Blood Group Reference Laboratory (IBGRL) within 7 days of venepuncture.
- from NHS England hospitals use routine NHSBT transport
- for other customers please send samples via 1^st class post or courier

To assist you with implementation of fetal RHD screening in your health trust, we will provide you with:

Examples of maternity pathways led by either clinical or laboratory-based teams
A calculation template to assess your cost analysis (savings)
An informative Q&A document based on our experience with helping other health trusts
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

Technical Aspects, limitations of the test and factors affecting test performance

During pregnancy a small amount of cell-free fetal DNA is present in maternal blood. This DNA can be analysed for RHD exons 5 and 7 using real-time polymerase chain reaction to predict the baby’s D blood group to see if it differs from that of the mother. The test is highly accurate and can be performed from 11⁺² weeks’ gestation (crown rump length ≥ 45mm). However, owing to the sensitivity of the test, there is a small chance (0.1%) that a fetus predicted to be D negative will be D positive at birth. Please inform the Molecular Diagnostics department as soon as possible if this occurs and send a sample of cord and mother’s blood if available. Owing to the presence of rare variant RHD genes, up to 2% of fetuses predicted to be D positive will in fact be D negative at birth.

Women who have been confirmed to be weak D or D variant are unlikely to benefit from the fetal RHD screening test because the maternal RHD gene will prevent prediction of fetal D phenotype and an inconclusive test result will be issued. Women who are confirmed weak D should be treated as D positive and prophylactic anti-D is not required. Women who are confirmed D variant should be given anti-D prophylaxis in line with local policy.

The amount of fetal DNA in maternal blood increases throughout gestation, therefore it is essential that maternal blood is not taken before 11⁺² weeks’ gestation. Samples taken too early in gestation will not be tested.

Blood samples which have significantly haemolysed may contain a very high background of maternal DNA which could interfere with detection of fetal DNA, therefore haemolysed samples will not be tested.

Samples from women carrying multiple babies can be tested. A D positive test result means that at least one fetus is predicted to be D positive. A D negative test result means that all the fetuses are predicted to be D negative.

Measurement uncertainty for the assays used in the laboratory has been established and is available upon request.

Molecular Diagnostics

More information about our services

Licensing and accreditation Customer surveys Red cell genotyping Fetal genotyping – diagnostic

User guide

Download our user guide for referring samples to IBGRL Molecular Diagnostics

INF1259.7 fetal RHD screen User Guide (PDF 446 KB) This document will open in a new window

Have a question?

Please contact the laboratory or our business development manager for more information:

If you wish to set up a contract to send samples or would like to obtain information regarding the tests performed, please contact Erika Rutherford.

For all other enquiries, please contact Molecular Diagnostics.