Tools and resources

1 Introduction

1 Introduction

This resource has been developed to provide practical information and advice on NICE diagnostics guidance on high-throughput non-invasive prenatal testing for fetal RHD genotype.

The information presented in this resource is intended for the sole purpose of supporting the NHS in adopting, evaluating the impact of adopting or further researching this technology. It is complementary to the guidance and was not considered by the diagnostic assessment committee when developing its recommendations.

The technology for high-throughput non‑invasive prenatal testing (NIPT) for fetal RHD genotype is a laboratory-developed test, offered by NHS Blood and Transplant (NHSBT), Bristol. Regional variations in terminology include cell-free fetal DNA (cffDNA), free fetal DNA (ffDNA) and fetal rhesus status testing. Some of these terms are used in this report in the context of local examples.

The technology uses a real-time quantitative polymerase chain reaction (PCR) method for identifying fetal RHD genotype from fetal DNA in the plasma of rhesus‑D (D) negative women. It can rapidly process batches of between 32 and 88 samples (see section 3 of the guidance).

The benefits of using high-throughput NIPT for fetal RHD genotype to guide antenatal prophylactic treatment with anti-D immunoglobulin as reported by the NHS staff involved in producing this resource include:

  • preventing unnecessary administration of blood products (anti‑D immunoglobulin) and their associated risk

  • avoiding unnecessary painful injections for women when the NIPT for fetal RHD genotype result is negative

  • reducing the number of antenatal anti‑D prophylactic clinic appointments needed, and the amount of anti‑D immunoglobulin used

  • increasing the availability of anti‑D immunoglobulin for use after potentially sensitising events in pregnancy when the NIPT result for fetal RHD genotype is positive

  • reducing the anxiety associated with potentially sensitising events for D‑negative women when the NIPT result for fetal RHD genotype is negative

  • providing information to allow D‑negative women to make an informed decision about whether to have treatment with anti‑D immunoglobulin.

NHS contributors also reported that services should be aware of the possibility of false-negative test results when deciding to introduce the test.

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