Which of the following is the most common cause of primary postpartum hemorrhage?

Explanation

## Causes of Primary Postpartum Hemorrhage **Key Point:** Primary postpartum hemorrhage (PPH) occurs within 24 hours of delivery. Uterine atony accounts for 50–60% of all cases and is the leading preventable cause. ### Frequency Distribution | Cause | Frequency | Mechanism | |-------|-----------|----------| | Uterine atony | 50–60% | Failure of myometrial contraction after placental delivery | | Genital tract trauma | 20–25% | Cervical, vaginal, or perineal lacerations | | Retained placental tissue | 10–15% | Incomplete placental separation or retained cotyledons | | Coagulopathy | 5–10% | Inherited or acquired clotting disorders | ### Why Uterine Atony Is Most Common 1. **Risk factors:** Grand multiparity, prolonged labor, polyhydramnios, macrosomia, use of uterotonic agents, general anesthesia 2. **Pathophysiology:** Loss of normal myometrial contraction → failure to compress bleeding vessels at placental bed 3. **Clinical presentation:** Boggy, soft uterus on palpation with heavy vaginal bleeding **High-Yield:** Uterine atony is the ONLY cause of PPH that is reliably preventable with active management of the third stage of labor (prophylactic oxytocin, controlled cord traction, uterine massage). **Clinical Pearl:** A firm, well-contracted uterus with continued heavy bleeding should prompt investigation for retained products or genital tract trauma, not assume atony.