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Prenatal diagnosis a case of 69, XXY with open spina bifida in the first trimester

VO Ta-Son
Vinmec Healthcare System, Hanoi, Vietnam
Posting Dates: Sep 20, 2025 - Sep 23, 2025
Axial planes of fetal head
Image 1 Axial planes of fetal head
Axial planes of fetal head
Image 2 Axial planes of fetal head
Mid-sagittal view of the brain
Image 3 Mid-sagittal view of the brain
Tricuspid flow
Image 4 Tricuspid flow
CRL
Image 5 CRL
Placenta
Image 6 Placenta
4CV
Image 7 4CV
3VT
Image 8 3VT
Placenta
Image 9 Placenta
Biometry
Image 10 Biometry
Video 1 Fetal heart © 2025 Vo Ta Son
Video 2 Fetal heart © 2025 Vo Ta Son

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Answer

A 13-week pregnant woman underwent routine prenatal screening. The non-invasive prenatal test (NIPT) showed low risk for common aneuploidies (trisomy 21, 18, and 13). However, first-trimester anomaly scan revealed the following significant fetal abnormalities:

  • Thin nasal bone
  • Open spina bifida in the sacral region with dry brain and crash sign, BS/BSOB >1, direct lesion at sacral coccygeal spine
  • Ventricular septal defect (VSD)
  • Tricuspid valve regurgitation
  • Right aortic arch
  • Cystic-appearing placenta, suggestive of partial molar changes

Given the discordance between the low-risk NIPT result and the concerning ultrasound findings, chorionic villus sampling (CVS) was performed for karyotype analysis.

Karyotype results revealed triploidy with a 69,XXY chromosomal complement, consistent with diandric triploidy (paternal origin). This finding correlated well with the ultrasound abnormalities, particularly the cystic placenta and multiple fetal structural defects.

A primary spinal lesion is observed in the sacral region, characterized by a posterior vertebral arch defect and a protruding meningeal sac.
Image 1 A primary spinal lesion is observed in the sacral region, characterized by a posterior vertebral arch defect and a protruding meningeal sac.
3D Image
Image 2 3D Image
Video 1 Coronal view of the spine © 2025 Vo Ta Son
Video 2 Sagittal view of the spine © 2025 Vo Ta Son
Spinal defect in the sacral region visualized on 3D ultrasound.
Image 3 Spinal defect in the sacral region visualized on 3D ultrasound.
Spinal defect in the sacral region visualized on 3D ultrasound.
Image 4 Spinal defect in the sacral region visualized on 3D ultrasound.
Video 3 Enlarged, cystic placenta © 2025 Vo Ta Son

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