The NHS is offering NIPT testing for women with a confirmed previous affected pregnancy with any full trisomy for chromosome 21, 18 or 13 via the National Genomic Test Directory under referral code R445.

Inclusion criteria

• All women with a history of pregnancy with a full trisomy of T21, T18 or T13 should be offered NIPT in any subsequent pregnancy.
• R445 is offered from 10+0 to 21+6 weeks inclusive, confirmed by ultrasound scan (USS), to both singleton and twin pregnancies.
• Eligibility for R445 should be established prior to offering the test. See the R445 test entry within the NGTD for latest eligibility and exclusion criteria.
• It is recommended that the report from the previous affected pregnancy is reviewed to confirm full trisomy of T21, T18 or T13 prior to offering R445. However, R445 can still be offered even if the previous report is unavailable or obtaining it will cause a delay in screening. In such cases it should be explained to the woman that R445 is being performed on the basis that the previous pregnancy was a full trisomy T21, T18 or T13 and not another chromosomal anomaly, as these will not be detectable by NIPT

Exclusions 

• Existing NHS FASP exclusions: vanished twin pregnancy, current maternal cancer, balanced translocation (T21, 18, 13), maternal T21, bone marrow/organ transplant, blood transfusion in the last 4 months.
• Previous pregnancy was a trisomy involving chromosomes other than T21, T18 or T13. – Previous pregnancy was not a full trisomy: e.g., mosaicism, translocation or, partial trisomy of T21, T18 or T13. – One of the parents has a Robertsonian translocation or balanced translocation involving chromosome T21, T18 or T13. – Donor egg used in current pregnancy. In these cases, referral to genetic counseling and / or fetal medicine should be offered.