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
Most common cause of primary post-paum hemorrhage is: 
Select and explain. 
A. Uterine atony, B. Uterine ineia, C. Uterine inversion, D. Retained placenta
A: Uterine atony
Answer: A: Uterine atony 
Explanation: Ans. a. Uterine atonyPrimary Postpaum Hemorrhage:Atonic uterus: Uterine atony is most common(80% cases)Grand multiparaOverdistension of the uterus as in multiple pregnancy, hydramnios & big babyUterine fibroidPlacenta: Morbidly adherent placenta(accrete, perceta)Antepaum haemorrhage(both placenta prae & abruption)Prolong labour , Mismanaged 3rd stage labour