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Updated: Aug 16, 2026
Murine Fetal Echocardiography
Published on: February 15, 2013
[Sonographic features of chromosomal defects at 11(+0) to 13(+6) weeks of gestation]
Kypros H Nicolaides1, Piotr Wegrzyn
1Harris Birthright Research Centre for Fetal Medicine, King's College Hospital Medical School, London, United Kingdom.
Insights
First-trimester ultrasound reveals increased nuchal translucency (NT) thickness in major chromosomal defects. Specific sonographic markers aid in identifying trisomy 21, trisomy 18, trisomy 13, Turner syndrome, and triploidy.
Area of Science:
- Prenatal Diagnosis
- Fetal Medicine
- Genetics
Background:
- Chromosomal defects present unique syndromic patterns of abnormalities.
- Early identification of fetal chromosomal abnormalities is crucial for timely intervention and genetic counseling.
Purpose of the Study:
- To describe the sonographic features of trisomy 21 and other major chromosomal defects during the first trimester of pregnancy.
- To correlate specific ultrasound markers with different chromosomal abnormalities between 11 and 13 weeks of gestation.
Main Methods:
- Sonographic assessment of fetal nuchal translucency (NT) thickness in the first trimester (11-13 weeks gestation).
- Identification and documentation of additional specific sonographic markers associated with major chromosomal defects.
- Correlation of ultrasound findings with confirmed chromosomal diagnoses.
Main Results:
- All major chromosomal defects were associated with increased NT thickness at 11-13 weeks.
- Trisomies 21, 18, and 13 showed similar NT patterns, averaging 2.5 mm above normal.
- Turner syndrome exhibited a median NT of 8 mm above normal.
- Specific markers included absent nasal bone in trisomy 21 and 18, fetal growth restriction, bradycardia/tachycardia, exomphalos, holoprosencephaly, and abnormal Doppler waveforms.
Conclusions:
- First-trimester NT thickness is a significant indicator for major chromosomal defects.
- Distinct sonographic features aid in differentiating between various chromosomal abnormalities.
- Early ultrasound markers can improve the detection rates of fetal chromosomal defects.
Abstract:
Each chromosomal defect has its own syndromal pattern of detectable abnormalities. The authors describe the sonographic features of trisomy 21 and other major chromosomal defects in the first trimesters of pregnancy. At 11(+0) - 13(+6) weeks, all major chromosomal defects are associated with increased NT thickness. In trisomies 21, 18 and 13 the pattern of increase in NT is similar and the average NT in these defects is about 2.5 mm above the normal median for crown-rump length. In Turner syndrome, the median NT is about 8 mm above the normal median. In addition to increased NT there are sonographic features that are often seen in some affected fetuses at 11(+0) - 13(+6) weeks. In trisomy 21 fetuses have absent nasal bone, short maxilla and abnormal Doppler waveforms in the ductus venosus. In trisomy 18, there is early onset fetal growth restriction, a tendency for bradycardia, exomphalos, absent nasal bone and single umbilical artery. In trisomy 13, there is tachycardia, early onset fetal growth restriction, megacystis, holoprosencephaly and exomphalos. In Turner syndrome, there is tachycardia and early onset fetal growth restriction. In triploidy, there is early onset asymmetrical fetal growth restriction, bradycardia, holoprosencephaly, exomphalos, posterior fossa cyst and molar changes in the placenta.
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