This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'A 35-year-old G4P3 at 18 weeks presents with sequential screening( Dual and then triple marker screening) of 1:170 for Down syndrome. You should do which of the following? \nSelect and explain. \nA. Offer CVS, B. Advise her the risk is quite small for aneuploidy, C. Perform a targeted ultrasound, D. Offer genetic counseling and perform Amniocentesis', 'role': 'user'}, {'content': "Answer: D \nExplanation: At age 35 should the patient should be offered genetic counseling and Amniocentesis. CVS is not appropriate at 18 weeks' gestation If required; the invasive test of choice here is Amniocentesis.", 'role': 'assistant'}]