What are the causes and pathogenesis of postpartum hemorrhage?

Postpartum hemorrhage (PPH) is defined as blood loss exceeding 500 mL within 24 hours after delivery of the fetus. Approximately 80% of cases occur within the first 2 hours postpartum. Late postpartum hemorrhage refers to massive uterine bleeding occurring after 24 hours post-delivery, during the puerperium—most commonly between days 1 and 2 weeks postpartum. PPH may occur before or after placental delivery. Clinically, it primarily manifests as vaginal bleeding, hypovolemic shock, secondary anemia, and, in severe cases, disseminated intravascular coagulation (DIC). Rapid, large-volume blood loss can precipitate shock within a short time; in the early stage of shock, compensatory physiological mechanisms may temporarily maintain vital signs.

Pathogenesis and Etiology of Postpartum Hemorrhagic Collapse

Sudden, massive vaginal bleeding following childbirth is termed “postpartum hemorrhagic collapse” in Traditional Chinese Medicine (TCM).

This condition corresponds closely to postpartum hemorrhage in Western medicine. It is associated with uterine atony, trauma to the soft birth canal, retained placental or fetal membrane fragments, and coagulopathy. If not treated promptly, it may lead to collapse (syncope) and even endanger the mother’s life—making it one of the most critical obstetric emergencies. In cases of massive postpartum vaginal bleeding caused by retained placental/membranous tissue or soft-tissue lacerations, timely surgical intervention is essential for hemostasis.

Etiology: The primary pathomechanisms involve Qi deficiency leading to impaired blood containment; blood stasis obstructing normal circulation; or damage to the vessels and collaterals.

In women with constitutional weakness or prolonged labor causing severe exhaustion and depletion of Yuan Qi (primordial Qi), Qi deficiency impairs its function of securing blood within the vessels, thereby triggering hemorrhagic collapse.

Blood stasis impedes smooth circulation, preventing blood from returning to its proper channels—resulting in uncontrolled hemorrhage. Excessive uterine contractions, precipitous labor, macrosomia, or direct trauma to the vessels and collaterals may also cause persistent bleeding and hemorrhagic collapse.