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
MC cause of secondary PPH is: 
Select and explain. 
A. Atonic uterus, B. Retained placenta, C. latrogenic injury, D. Medical diseases
B: Retained placenta
Answer: B: Retained placenta 
Explanation: Retained placenta