Nuchal Translucency Measurements in Antenatal Screening for Down's Syndrome
Author Information
Author(s): J P Bestwick, W J Huttly, N J Wald
Primary Institution: Wolfson Institute of Preventive Medicine, Barts and the London Queen Mary's School of Medicine and Dentistry
Hypothesis
Has the standard deviation of nuchal translucency (NT) measurements decreased over time, and how does this affect antenatal screening for Down's syndrome?
Conclusion
The standard deviation of NT has declined over time, and using revised estimates improves the screening performance of tests that incorporate NT measurement.
Supporting Evidence
- The standard deviation of NT in unaffected pregnancies has reduced over time.
- Using revised NT standard deviations resulted in a 20% decrease in the false-positive rate for a given detection rate.
- At 12–13 weeks gestation, the revised standard deviation of log10 NT MoM represents a 31% decrease in variance compared to previous estimates.
Takeaway
Doctors measure a part of the baby called nuchal translucency to check for Down's syndrome. Over the years, the measurements have become more accurate, which helps in better screening.
Methodology
Data from a routine antenatal screening program for Down's syndrome was analyzed, comparing NT measurements in affected and unaffected pregnancies.
Potential Biases
Potential bias in measurements due to clinical actions taken based on high NT values.
Limitations
The study did not observe a declining trend in standard deviation for Down's syndrome pregnancies due to insufficient data.
Participant Demographics
The study included 22,719 women attending antenatal clinics in London, with 106 pregnancies affected by Down's syndrome.
Statistical Information
P-Value
0.024
Statistical Significance
p<0.001
Digital Object Identifier (DOI)
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