Which circumstance is most likely to cause uterine atony and postpartum hemorrhage?

• A. Hypertension
• B. Urine retention
• C. Cervical and vaginal tears
• D. Endometritis

Answer: (B)

Uterine atony happens when the uterus doesn’t contract firmly after delivery, so it can’t compress the blood vessels and stop bleeding. A full bladder from urine retention keeps the uterus displaced and can physically interfere with effective uterine contractions, making atony more likely. Emptying the bladder helps the uterus contract toward the midline and reduces the risk of postpartum hemorrhage. Hypertension, cervical/vaginal tears, and endometritis don’t directly cause the uterus to fail to contract in the immediate postpartum period—their bleeding patterns come from other mechanisms (systemic risk, local injury, or infection/involution issues) rather than a flaccid uterus.