Screening For Abnormalities

screening for abnormalities-ultrasound

Whilst most pregnancies progress well and a normal happy outcome should be anticipated, occasionally a pregnancy may be affected by genetic or structural abnormalities. Testing is available to try to identify any of these risks. Some testing may be done prior to pregnancy, particularly if the parents are suspected of carrying a genetic disease. More commonly testing is offered at 10-14 weeks of pregnancy to calculate the risk of Down syndrome (Trisomy 21) and some other genetic conditions. These options include :

  • Choosing no testing at all
  • Nuchal Translucency Screening. This involves a blood test on the mother and an ultrasound at 12 weeks to measure the baby’s neck skin thickness. A risk estimate can then be calculated.
  • NIPT / Harmony Testing. This is simply a blood test on the mother after 10 weeks where tiny fragments of the baby’s cell free DNA can be extracted to evaluate whether the child is at higher risk of Trisomies 13,18 or 21. The sex of the baby may be determined also. Although more expensive, NIPT / Harmony testing is also more accurate than Nuchal Translucency testing.
  • Amniocentesis or Chorionic Villus Sampling. A needle is passed into the mother’s abdomen to collect a biopsy of the placenta (CVS) or sample of amniotic fluid (Amnio). The results are essentially 100% accurate for chromosomal disorders, but they do carry a small risk of causing a miscarriage, therefore are usually not performed as “first-line” tests.
  • 19 Week Morphology Ultrasound. This scan examines the structural appearance of the baby from head to toe, to help identify if any abnormalities are present.