This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
Cause of secondary PPH is 
Select and explain. 
A. Atonic uterus, B. Retained placental bits, C. Ruptured uterus, D. Cervical laceration
B: Retained placental bits
Answer: B: Retained placental bits 
Explanation: Causes of secondary PPH: Retained bits of cotyledon or membranes Infection and separation of slough over a deep cervicovaginal laceration Endometritis Hemorrhage from cesarean section wound Withdrawal bleeding following estrogen therapy for suppression of lactation Ref: Dutta Obs 9e pg 392.