This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'What is the significance of increased nuchal translucency at 14 weeks of gestation? \nSelect and explain. \nA. Oesophageal atresia, B. Foregut duplication cyst, C. Downs syndrome (Trisomy 21), D. Edwards syndrome (Trisomy 18)', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Nuchal translucency(NT) is a term used to describe a sonolucent area in the nuchal region (back of the neck) of the fetus and is typically observed in the first trimester (10-14weeks). Increased NT refers to NT measurement of greater than 2.5mm. One third of fetus with increased nuchal translucency will have a chromosome abnormality, and 1/2 of these are Down syndrome. Ref: Williams Obstetrics 23rd Edition Chapter 13; Obstetrics, Gynecology & Infeility By R Rajan Page 225-6; Textbook of Obstetrics By D. C Dutta, 6th Edition, Page 107.', 'role': 'assistant'}]