What is the primary cause of secondary post-partum hemorrhage?

The primary cause of secondary postpartum hemorrhage is indeed retained placental tissue. After delivery, the uterus undergoes significant changes to involute and return to its pre-pregnancy state. If fragments of the placenta or membranes remain in the uterus, it can lead to continued bleeding. This retained tissue can prevent the uterus from contracting effectively, resulting in prolonged hemorrhage that can occur days or even weeks after the initial delivery.

Understanding the pathophysiology behind retained placental tissue is important; it maintains a state of uterine atony, leading to an inability of the uterus to properly contract and reduce blood loss. This can be particularly critical because retained placental tissue can also provide a breeding ground for infection, contributing to further complications. Recognizing this risk factor helps healthcare professionals manage and monitor postpartum patients effectively to prevent serious outcomes.