This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Karyotyping of fetus can be done through all of the following invasive methods except: \nSelect and explain. \nA. Amniocentesis, B. Cordocentesis, C. Chorionic villous sampling, D. fetal skin biopsy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Invasive methods of prenatal diagnosis: In Chorion villus sampling, Amniocentesis and Cordocentesis fetal cells are obtained for karyotyping.Fetoscopy is done at 16-20 weeks, for visualization of fetal external anatomy and for fetal skin or muscle biopsy for diagnosis of genetic disorders (Meckel-Gruber syndrome). Reference:Dutta,s Textbook of obstetrics 7th edition page no 494', 'role': 'assistant'}]