Combined first trimester screening or CFTS
CFTS is performed between 9+0 and 13+6 weeks (ie. 13 weeks and 6 days gestation). If also screening for early-onset pre-eclampsia, your gestation should be between 11+0 and 13+6 weeks).
This test combines a few different measures to give the result.
- Blood to measure two chemicals called PAPP-A and free beta hCG.
- A nuchal translucency ultrasound (NT scan) between 11+0 and 13+6 weeks.
- Your weight, age, IVF details and any relevant medical history
- Presence or absence of the baby’s nasal bone (as seen by ultrasound).
This is a blood test done between 14+0 and 20+6 weeks gestation (15-17 weeks is best).
Four chemicals are measured:
- alpha-feto protein
- unconjugated estriol
- free beta hCG and
- dimeric inhibin A.
These results are combined with your age, weight and gestation to give a result.