Skeletal abnormalities in fetuses with Down's syndrome: a radiographic post-mortem study.

Area of Science:

• Prenatal Diagnosis
• Medical Imaging
• Genetics

Background:

• Down syndrome (trisomy 21) is a common chromosomal abnormality.
• Prenatal detection of Down syndrome relies on various markers.
• Skeletal abnormalities can be identified through fetal imaging.

Purpose of the Study:

• To evaluate specific skeletal abnormalities in fetuses with Down syndrome using post-mortem radiographs.
• To assess the utility of these skeletal markers for prenatal screening of trisomy 21.

Main Methods:

• Radiographic analysis of limb long bones, biparietal diameter/occipito-frontal diameter ratio, nasal bone ossification, and middle phalanx of the fifth digit (P2).
• Comparison between 60 fetuses with Down syndrome and 82 normal fetuses.
• Analysis across gestational ages from 15 to 40 weeks' gestation.

Main Results:

• Reduced limb long bone growth velocity observed in the third trimester, more pronounced in trisomic fetuses.
• Brachycephaly detected from 15 weeks' gestation in Down syndrome fetuses (sensitivity 0.28, specificity 1).
• Absent nasal bone ossification in 25% of trisomic fetuses; P2 ossification/hypoplasia noted in 55% after 24 weeks' gestation (sensitivity 0.56, specificity 1).

Conclusions:

• Brachycephaly, absent nasal bone ossification, and hypoplastic middle phalanx of the fifth digit are significant skeletal indicators of Down syndrome.
• These skeletal signs are suitable for prenatal ultrasound screening.
• The presence of these markers warrants fetal karyotype determination via amniocentesis.