Etiology
Uterine atonicity
It is the most common cause of postpartum hemorrhage contributing to about 80% of all PPH cases. It is caused by:
Overdistension of the uterus due to polyhydramnios, Multiple pregnancy or molar pregnancy.
Grand multiparity
Prolonged labor
Anesthesia, deep anesthesia and some drugs such as halothane and ether can cause atonicity.
Trauma
It may involve the cervical, vaginal or perineal tears and uterine rupture. The bleeding is usually revealed but it can rarely be concealed (as in vulvovaginal or broad ligament hematoma).It can also be caused by Large episiotomy and extensions.
Retained placental tissue
It involves partial separation of the placenta leaving behind portions of placenta, blood clots which causes PPH due to imperfect uterine retraction. It can also be caused by morbid adhesion such as Accreta, Increta & Percreta
Coagulation disorders
Ā are more common in intra uterine fetal death(IUFD), placental abruption, sepsis, massive blood transfusion, severe pre eclampsia, disseminated intravascular coagulopathy (DIC), and in those with a history of an inherited coagulation defect.