## **Core Concept**
Secondary postpartum hemorrhage (PPH) refers to excessive bleeding that occurs after 24 hours postpartum, typically up to 6 weeks after delivery. The causes can be uterine atony, retained placental tissue, infection, or coagulopathy.

## **Why the Correct Answer is Right**
Uterine atony is a leading cause of primary postpartum hemorrhage, which occurs within the first 24 hours after delivery. It results from the failure of the uterus to contract down effectively after childbirth, leading to excessive bleeding.

## **Why Each Wrong Option is Incorrect**
* **Option A:** Retained placental tissue can cause secondary PPH due to infection or continued bleeding from the site where the placenta was not fully expelled.
* **Option B:** Infection, such as endometritis, can lead to secondary PPH through tissue destruction and coagulopathy.
* **Option D:** Coagulopathy can cause or contribute to both primary and secondary PPH by impairing the body's ability to form clots.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that secondary PPH often presents with a more insidious onset of symptoms compared to primary PPH. Healthcare providers should maintain a high index of suspicion for causes like retained products of conception and infection.

## **Correct Answer:** . Uterine atony