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': 'The foetal pole with cardiac activity is detected with Transvaginal USG by what stage of gestation? \nSelect and explain. \nA. 6 weeks, B. 8 weeks, C. 10 weeks, D. 12 weeks', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Using transvaginal USG, the gestational sac can usually be seen at 4 weeks, the yolk sac at 5 weeks, and the fetal pole with cardiac activity by 6 weeks. Cardiac activity can be seen simultaneously with the appearance of a fetal pole as a pulsation at the lateral aspect of the yolk sac. Normal embryonic hea rate may be as low as 70-100 beats per minute range during early gestation, but soon rises to the fetal normal range of 120-160 beats/min by 9-10 weeks gestational age.', 'role': 'assistant'}]