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Fetal transcerebellar diameter in Down syndrome
S Rotmensch1, I Goldstein, M Liberati
1Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut, USA.
Obstetrics and Gynecology
|April 1, 1997
Summary
Cerebellar hypoplasia is detectable in second-trimester fetuses with Down syndrome. However, the small size differences are not clinically useful for screening Down syndrome during pregnancy.
Area of Science:
- Prenatal Diagnosis
- Fetal Development
- Genetics
Background:
- Down syndrome is a genetic condition associated with various developmental abnormalities.
- Cerebellar hypoplasia has been anecdotally reported in Down syndrome but its establishment in early pregnancy is unclear.
Purpose of the Study:
- To ascertain if cerebellar hypoplasia is present and detectable in the second trimester for fetuses with Down syndrome.
- To assess the effectiveness of transverse cerebellar diameter measurements in screening for Down syndrome.
Main Methods:
- Retrospective analysis of ultrasonographic biometry data from 42 Down syndrome fetuses and 1161 normal fetuses.
- Comparison of mean transverse cerebellar diameters adjusted for gestational age.
- Calculation of observed-to-expected cerebellar diameter ratios and diagnostic performance metrics.
Main Results:
- Fetal cerebellar diameters were significantly smaller in Down syndrome cases compared to controls across all gestational ages (P < .005).
- A threshold ratio of 0.92 demonstrated 21% sensitivity and 95% specificity for Down syndrome detection.
Conclusions:
- Cerebellar hypoplasia is an established condition in second-trimester fetuses with Down syndrome, detectable via ultrasound.
- The subtle size differences render cerebellar measurements clinically impractical for routine Down syndrome screening.