Presentation: Patient with a higher-chance non-invasive prenatal test (NIPT) result

A couple have opted to have non-invasive prenatal testing (NIPT) following a combined screening result that gave an increased chance (1 in 20) of Down syndrome (trisomy 21). The couple have just been given the results of that NIPT, which are in keeping with their combined screening results in that they show a higher chance of trisomy 21.

• All women who have a higher-chance NIPT result (as defined above) should be offered the option of genomic testing.
• If the first NIPT sample gives no result or the sample is rejected, the patient should be offered the option of a further NIPT sample or genomic testing.
• If the second sample also fails to give a result, the patient should be given the option of diagnostic genomic testing.

• Refer to local guidance regarding higher-chance NIPT discussion and fetal medicine referral.
• Referral to clinical genetics is not routinely indicated for a higher-chance NIPT result. A review by fetal medicine teams will determine whether genomic testing is appropriate, and referral to clinical genetics can be considered in certain circumstances.
• The relevant team will refer to the NHS England National Genomic Test Directory eligibility criteria to determine which tests are available for your patient. The directory itself provides a list of all available tests.
  • For those working within NHS Wales, please consult the All Wales Medical Genomics Service website for information on how to arrange testing.
• Decide which testing is most suitable for the specific clinical scenario and for your patient.
  • If there is an isolated higher-chance NIPT result in a fetus that appears otherwise structurally normal for that gestation:
    • R401: Genome-wide common aneuploidy testing (QF-PCR).
  • If there are structural anomalies present in addition to a higher-chance NIPT result, further testing may be relevant:
    • R22: Fetus with a likely chromosomal abnormality. This will process a chromosomal microarray alongside the QF-PCR.
  • Although it is unlikely to be required in this scenario, if there are multiple or complex anomalies fetal exome sequencing may be considered following discussion with tertiary fetal medicine and clinical genetics teams.
    • R21: Fetal anomalies with a likely genetic cause: Rapid fetal exome sequencing.
    • A record of discussion form is required.
• For DNA-based tests (including all the above tests), an EDTA sample is required. For many of the tests (particularly whole genome and exome sequencing), parental samples are also needed or are helpful. Please refer to your local Genomic Laboratory Hub for details of test request forms and where to send samples.
• Information about patient eligibility and test indications was correct at the time of writing. When requesting a test, please refer to the National Genomic Test Directory to confirm the right test for your patient.

For clinicians

• NHS England: National Genomic Test Directory and eligibility criteria
• St George’s University of London: Non-invasive prenatal testing (NIPT): An introduction for healthcare professionals

For patients

• Antenatal Results and Choices: Non-invasive prenatal testing (NIPT) information
• St George’s University Hospitals NHS Foundation Trust: Non-invasive prenatal testing (NIPT) (PDF, two pages)