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Trisomy 21 in both fetuses in a DCDA twin pregnancy
  1. Jiawen Ong1,
  2. Arundhati Gosavi2,
  3. Arijit Biswas2 and
  4. Mahesh Choolani2
  1. 1 Obstetrics and Gynaecology, KK Women’s and Children’s Hospital, Singapore
  2. 2 Obstetrics and Gynecology, National University Hospital, Singapore
  1. Correspondence to Dr Jiawen Ong, ongjiawen94{at}


A woman’s chances of having a child with Down syndrome increases with age. By age 40, the risk of conceiving a child with Down syndrome is about 1 in 100. We report a rare case of dizygotic dichorionic diamniotic twin pregnancy conceived via in vitro fertilisation, with both twins having trisomy 21. Both fetuses were independently detected to be at high risk of autosomal trisomy, initially via first-trimester screening and subsequently via invasive definitive diagnostic tests (ie, chorionic villus sampling and amniocentesis).

Diagnosis of trisomy 21 has to be made via initial non-invasive prenatal screening, followed by further rigorous and accurate invasive pregnancy testing for confirmation. The gravity of the results necessitates high detection rates and high specificity of prenatal screening tests. Management of the patient must be multidisciplinary and supportive in nature, involving extensive and non-directive pregnancy counselling and management, genetic counselling and management of psychological distress.

  • reproductive medicine
  • pregnancy

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  • Contributors JO: discussed, summarised and wrote the case report. AG: discussed and reviewed the case report. AB: reviewed the case report. MC: reviewed the case report; patient’s doctor in charge.

  • Funding The authors are not associate with any specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Patient consent for publication Obtained.