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Articles » Aneuploidy » Trisomy 18

2006-06-12-10 Trisomy 18 © Cuillier

Trisomy 18  

Fabrice Cuillier, MD*, Lemaire P**, Deshayes M***

* Dept of Obstetrics and Gynecology, Hôpital Félix Guyon ** Sonographer, Moufia"s street, Reunion Island, France

Case report: This is a 30-year-old woman, G2P2. The first scan was performed at 13 weeks. The nuchal translucency was normal (1.5 mm). The ultrasound findings were:

  • an abnormal brain
  • a triple leaf on the middle of the brain
  • normal thalami
  • normal falx
  • abnormal posterior fossa
  • disorganized brain anatomy 
  • no hypo or hypertelorism
  • single umbilical artery 
  • bilateral abnormal hands, with fixed fingers
  • normal feet

The patient was informed about these fetal anomalies. An amniocentesis was performed  (karyotype = Trisomy 18). An interruption of pregnancy was performed. The brain was fixed on Formol and was sent to Paris for anatomic-pathological examination (Dr Delezoide, Robert Debre Hospital).

The brain was described as "diencephalon-rhombencephalic dysplasia". Between the thalami, the third ventricle was not observed, but an inter-hemispheric cyst was present. The corpus callosum was not seen and there was a stenosis of Sylvius‘s aqueduct. A cerebellum and pontine dysplasia was described. According to the anatomopathologist, this brain dysmorphogenesis was not usual for Trisomy 18. Chemotherapy could explain this dysplasia, but the patient denied use of medications.


Endovaginal scan at 14 week showing the flat face


Endovaginal scan at 14 weeks showing thalami which are not fused

Brain images at 14 weeks: Note the unusal structure...

Normal eyes

Single umbilical artery

Right and left hands with fixed fingers

Normal feet

Post-natal view