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
When would you do trans-vaginal sonography in post-menopausal bleeding if endometrial thickness is? 
Select and explain. 
A. 5mm, B. 7mm, C. 4mm, D. 9mm
A: 5mm
Answer: A: 5mm 
Explanation: Ans. A. 5mmRef: RCOG guidelines 2012