[Fetal nuchal translucency measurements in women aged 35 and older. Results from 1.1. 99-31.12.00.].
OBJECTIVE
Based on a combination of ultrasound fetal nuchal translucency measurement at 11-13 weeks and maternal age, a risk assessment for fetal aneuploidy is calculated. This method identifies a subgroup at risk for fetal aneuploidy, with less invasive testing while increasing the number of fetal aneuploidy cases diagnosed, compared to the current approach in Iceland where fetal aneuploidy risk is based on maternal age only.


METHODS
All women who presented for an ultrasound and counselling in preparation for an amniocentesis, the majority for advanced maternal age, were offered nuchal translucency measurement and risk assessment for fetal aneuploidy.


RESULTS
In 1999 a total of 477 nuchal translucency measurements were performed. Ten fetuses (2.1%) had risk assessment for fetal aneuploidy above 1:300 leading to diagnosis of 5/6 (83%) trisomy 21 cases and two other fetal aneuploidy cases within the group. Three fetuses who had increased nuchal translucency and normal karyotype were normal at birth. Three women who underwent an amniocentesis in spite of risk assessment less then 1:300 had aneuploid fetuses. Ultrasound and nuchal translucency measurement lead to the diagnosis of 7/10 fetal aneuploidy cases within the group. In 2000 a total of 418 nuchal tranlucency measurements were performed. Nine fetuses (2.15%) had risk assessment for fetal aneuploidy above 1:300 leading to diagnosis of 1/1 trisomy 21 case and 2/2 other fetal aneuploidy cases within the group. One fetus had multiple anomalies and the pregnancy was terminated without prior karyotyping. Of the five fetuses who had a normal karyotype one had cardiac abnormality and one an omphalocele. The remaining three were healthy at birth. Ultrasound and fetal nuchal translucency measurements lead to the diagnosis of all fetal aneuploidy cases within the group.


CONCLUSIONS
During 1999 and 2000 ultrasound and fetal nuchal translucency measurements in a selected subgroup at risk for fetal aneuploidy lead to the diagnosis of 7/10 and 3/3 fetal aneuploidy cases with 2.1% positive screen rate.
Harðardóttir
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Obstetrics and Prenatal Diagnosis Unit, Landspitali University Hospital, Hringbraut, 101 Reykjavík, Iceland. hhard@landspitali.is.