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Changes in nuchal translucency thickness in normal and abnormal karyotype fetuses
Maria A Zoppi1, Rosa M Ibba, Marcella Floris
1Department of Obstetrics and Gynecology, Prenatal and Preimplantation Genetic Diagnosis, Fetal Therapy, Ospedale Microcitemico, Cagliari, Italy.
Summary
In fetuses with abnormal karyotype, the second nuchal translucency measurement tends to increase or remain unchanged. Normal karyotype fetuses typically show a reduced nuchal translucency, aiding in prenatal diagnosis.
Area of Science:
- Prenatal diagnosis
- Fetal medicine
- Genetics
Background:
- Nuchal translucency (NT) is a key marker in first-trimester screening for chromosomal abnormalities.
- Dynamic changes in NT thickness can provide further insights into fetal karyotype status.
Purpose of the Study:
- To investigate the dynamic trend of nuchal translucency (NT) thickness in fetuses with normal versus abnormal karyotypes.
- To compare NT changes between fetuses with normal and abnormal karyotypes during the first trimester.
Main Methods:
- Prospective observational study of 305 first-trimester fetuses.
- Second NT measurements were performed on fetuses with NT ≥ 95th centile.
- NT findings ('increased or unchanged' vs. 'diminished') were compared between normal and abnormal karyotype groups.
Main Results:
- Abnormal karyotype fetuses (n=66) showed increased/unchanged NT in 56% and diminished NT in 44%.
- Normal karyotype fetuses (n=226) showed increased/unchanged NT in 25% and diminished NT in 75%.
- The relative risk of increased/unchanged NT in abnormal karyotype fetuses was 2.6 (95% CI 1.7-4.0).
Conclusions:
- Fetuses with abnormal karyotypes tend to exhibit increased or unchanged nuchal translucency on a second measurement.
- Conversely, fetuses with normal karyotypes typically show a reduction in nuchal translucency thickness.
- These dynamic NT changes can potentially improve the accuracy of prenatal screening for fetal aneuploidies.