(681) Fetuses with increased nuchal translucency before 11 weeks are at risk of abnormal pregnancy outcome

Friday, February 10, 2023

10:30 AM – 12:00 PM

Objective: An increased nuchal translucency (NT) ≥3.5mm is a reliable marker for chromosomal- and structural anomalies between 11 and 13+6 weeks' gestation. Little is known about its performance as a screening tool before 11 weeks.

Study Design: This is an ongoing prospective cohort study including pregnant women with a viable fetus with a crown rump length (CRL) < 45mm and a NT ≥2.5mm. All women are referred to our fetal medicine unit (FMU) one week later where the NT is remeasured with CRL >45mm. Two groups are constructed: one in which the NT has normalized (< 3.5mm) and one with a persistently increased NT (≥3.5mm). Cases are monitored until 4 weeks after delivery. The main outcome is a composite adverse outcome of pregnancy loss, chromosomal- and structural anomalies. Subgroup analyses are made based on normalized or persistently increased NT at follow-up, and for NT thickness at inclusion.

Results: To date 92 cases are included. Mean CRL and NT at inclusion and follow-up are 38.6 ±4.2mm and 3.9 ±1.1mm, and 52.7 ±4.8mm and 3.5 ±2.5mm, respectively. In the normalized NT group an abnormal outcome was found in 8/56 (14%), of which 5 aneuploidies (9%). This was significantly different (p< .000, OR 10.1) compared to the persistently increased NT group, with an abnormal outcome in 22/35 (63%), of which 14 aneuploidies (41%). Subgroup analysis based on NT thickness at inclusion showed an abnormal outcome in 6/27 (22%), 12/33 (36%) and in 9/20 (45%) in cases with an NT of 2.5-3.5mm, 3.5-4.5mm and >4.5mm, respectively.

Conclusion: Fetuses with an early increased NT thickness are at risk of an abnormal pregnancy outcome, even if the NT normalizes after 11 weeks. The risk of aneuploidies in this group is significantly higher compared to baseline (9% vs 0.9, respectively). Our preliminary study results showed, that expectant parents should be referred to a FMU for detailed ultrasonography and invasive diagnostic should be offered, if an thickened NT is seen with “eye-balling” during a dating scan, even before 11 weeks.

Primary Author(s)

B.B. Bet, MD (she/her/hers)
Department of Obstetrics and Gynecology, Amsterdam UMC, location University of Amsterdam
Amsterdam, Noord-Holland, Netherlands

Presenting Author(s)

B.B. Bet, MD (she/her/hers)
Department of Obstetrics and Gynecology, Amsterdam UMC, location University of Amsterdam
Amsterdam, Noord-Holland, Netherlands

Coauthor(s)

ML
M.A. Lugthart, MD
Department of Obstetrics and Gynecology, Amsterdam UMC, location University of Amsterdam
Amsterdam, Noord-Holland, Netherlands
IL
I.H. Linskens, MD, PhD
Department of Obstetrics and Gynecology, Amsterdam UMC, location Vrije Universiteit
Amsterdam, Noord-Holland, Netherlands
Lv
Liesbeth van Leeuwen, MD, PhD
Department of Obstetrics and Gynaecology, Amsterdam UMC location University of Amsterdam
Amsterdam, Noord-Holland, Netherlands
Eva Pajkrt, MD, PhD (she/her/hers)
Head of Obstetrics
Department of Obstetrics and Gynecology, Amsterdam UMC, location University of Amsterdam
Amsterdam, Noord-Holland, Netherlands