A GP guide to first-trimester aneuploidy screening

With a variety of first-trimester aneuploidy screening options available, counselling about what potential results could mean is especially important

Need to know:

  • All pregnant women, regardless of maternal age, should be offered aneuploidy screening.
  • Appropriate first-line screening options include either combined first-trimester screening (cFTS) at 11-13+ weeks — including nuchal translucency ultrasound, pregnancy-associated plasma protein A (PAPP-A) and human chorionic gonadotropin — or cell-free DNA (NIPT) blood test from 10 weeks.
  • Advantages of NIPT include its high positive predictive value with low false-positive rate for trisomy 21, 18 and 13, as well as its simplicity from a patient perspective (blood test only).
  • Advantages of cFTS include the opportunity for simultaneous early anatomy and pre-eclampsia screening ultrasound.
  • A 12-14 week ‘early anatomy’ ultrasound is valuable even if the woman has already had an NIPT. With 3% of pregnancies being affected by a major structural anomaly, many of which are not associated with aneuploidy, it can provide key