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
The best period of gestation to carry out chorion villous biopsy for prenatal diagnosis is? 
Select and explain. 
A. 8-10 weeks, B. 10-12 weeks, C. 12-14 weeks, D. 14-16 weeks
B: 10-12 weeks
Answer: B: 10-12 weeks 
Explanation: Chorionic villus sampling (CVS) is carried out transcervical between 10-12 weeks and trans-abdominal from 10 weeks to term. Ref:Textbook of Gynecology By D C Dutta, 5th Edition, Page 315