NIPT via the Fetal Aneuploidy Screening Programme

NIPT has been added to the existing NHS screening pathway for Down syndrome, Edwards syndrome and Patau syndrome as part of an evaluative rollout.

NIPT is now offered following a higher chance result (between 1 in 2 and 1 in 150) from either the NHS combined or NHS quadruple test in both singleton and twin pregnancies.

TDL Genetics perform this testing within Health Services Laboratories (HSL) who are part of the North Thames Genomic Laboratory Hub (GLH).

The following information is provided for midwives and healthcare professionals within the geographical region assigned to HSL.

NHS FASP Pathway

Following a higher chance result from the NHS combined or NHS quadruple test, women must have a discussion with a healthcare professional about their results. Women can choose to have:

• no further testing
• NIPT screening
• prenatal diagnosis (PND), such as chorionic villus sampling (CVS) or amniocentesis

For women choosing to have NIPT, the options available to screen for are:

• T21, T18 and T13
• T21 only
• T18 and T13 only

NIPT screening will report individual chance results for T21, T18 and T13.

 

Eligibility

Inclusions

As part of the NHS FASP evaluative rollout, NIPT can be offered and performed:

• when a woman receives a higher chance result for T21 or a joint higher chance result for T18 and T13 from the NHS combined test
• when a woman receives a higher chance result for T21 from the NHS quadruple test
• in both singleton and twin pregnancies
• up to 21 weeks and 6 days (21⁺⁶) of pregnancy

Women with in-vitro fertilisation (IVF) or donor egg pregnancies are eligible for the offer of NIPT. The relevant details must be recorded accurately on the NIPT screening request form.

 

Exclusions

As part of the NHS FASP evaluative rollout, NIPT cannot be offered and performed:

• when a woman receives a lower chance result for T21, T18 or T13 from the NHS combined or NHS quadruple test
• in higher multiple pregnancies (triplets or more)
• after 21⁺⁶ weeks of pregnancy

Also, NIPT cannot be offered and performed as part of the NHS FASP pathway when a pregnant woman has:

• cancer, unless in remission, as NIPT may detect cell free DNA (cfDNA) in the maternal blood which is released by a cancerous tumour
• received a blood transfusion in the previous 4 months, as studies show that donor DNA in blood transfusion recipients lasts for several months, sometimes longer
• had bone marrow or organ transplant, as donor DNA will be present
• immunotherapy in the current pregnancy, excluding intravenous immunoglobulin (IVIg) treatment
• had stem cell therapy, as this will depend on whether she has received her own stem cells or stem cells from a donor (certain methods of NIPT are not suitable for stem cell transplants)
• a vanished twin pregnancy (an empty second pregnancy sac or a second pregnancy sac containing a non-viable fetus), as there is evidence to suggest that the placenta can continue to shed cell free fetal DNA (cffDNA) even after the baby has died
• Down’s syndrome or a balanced translocation or mosaicism of T21, T18 or T13

 

Blood sampling and transport

Blood sampling

The process for obtaining an NIPT blood sample is as outlined below.

1. Take blood sample using cell stabilising tube provided by the individual laboratory, in line with the requirements outlined below.
2. Mix immediately by inverting at least 10 times for all samples.
3. If the venepuncture is unsuccessful or if you obtain less than the required full sample at the first attempt, discard and start again with a fresh cell stabilising tube.
4. After a second attempt if you are still unable to obtain a full sample, contact the individual laboratory for further guidance.
5. One full Streck cell stabilising tube (minimum 7ml of blood) is required

NIPT samples must not be refrigerated.

 

Transporting the sample

HSL provide:

• specialist cell stabilising tubes
• NIPT request forms
• packaging for sample transport
• the method of sample transport from the maternity service to the laboratory

The process for transporting an NIPT blood sample is outlined below.

1. Place the NIPT blood sample (specimen tube) into protective packaging provided by the laboratory. Do not refrigerate.
2. Put the protective packaging, with the NIPT laboratory request form, into P650 and UN3373 compliant transport packaging provided by the individual laboratory. Do not refrigerate.
3. The requestor should inform the NIPT laboratory that a sample is being sent to them for analysis by emailing nhsfasp@hslpathology.com. Samples should be received by the NIPT laboratory in ≤ 2 working days from the day of collection. Day of sample draw is counted as day 0. Samples are stable for 5 days so can be processed if they arrive within 5 days after blood collection.

 

Reporting NIPT results

All women who receive a higher chance NIPT result must be offered the option of:

• PND
• no further testing

In some cases, NIPT may fail to give a result. ‘No result’ is where a ‘fit for analysis’ sample was received in the laboratory and it has failed to generate a result at any point of the analytical or reporting process.

In cases where ‘no result’ is obtained from the initial NIPT sample, providers must offer:

• one further NIPT sample
• PND
• no further testing

NIPT may fail again on the second sample.

A woman must be ≤ 21⁺⁶ weeks of pregnancy when the first NIPT sample is taken.

A second NIPT sample can be offered and taken even if the woman is more than 21⁺⁶ weeks, in the following cases when a:

• sample is rejected
• ‘no result’ report is issued

Reports will be sent by encrypted email.

 

NIPT results

NIPT results are reported as either lower chance or higher chance. A numerical value is not reported.

NIPT results must only be reported according to the woman’s choice on the conditions screened for. For example, a lower or higher chance result at term for:

• T21, T18 and T13
• T21 only
• T18 and T13 only

NIPT screening will report individual chance results for T18 and T13. This is unlike the combined test which reports a joint chance result for these conditions. For example, when a woman chooses NIPT screening for T18 and T13 she will receive both:

• a lower or higher chance result for T18
• a lower or higher chance result for T13

In twin pregnancies, the higher chance result report should state that one or both babies may have the condition screened for.

Further information regarding the NHS NIPT FASP can be found here: https://www.gov.uk/government/publications/screening-for-downs-syndrome-edwards-syndrome-and-pataus-syndrome-non-invasive-prenatal-testing-nipt/screening-for-downs-syndrome-edwards-syndrome-and-pataus-syndrome-nipt

As the FASP NIPT programme is at an evaluative stage information on the performance of NIPT in a general mixed risk population may not be accurate to provide to women with a higher chance result from prior screening tests.

Women should be provided with the Screening tests for you and your baby information leaflet rather than information aimed at a mixed or lower chance population. A link to this information leaflet can be found here: Screening tests for you and your baby (STFYAYB) - GOV.UK (www.gov.uk)

Click here to download the HSL NIPT FASP request form

This form must only be used by maternity units who have been assigned to HSL for NIPT FASP testing.

Women who are not eligible for NIPT via the FASP pathway may still access NIPT privately. Please contact nipt@tdlpathology.com to discuss sending private referrals.