A healthy 32-year-old female just delivered a full-term neonate. After delivery of the placenta, she continues to have significant bleeding. You feel a grapefruit-sized mass in her lower abdomen that is painful when palpated. You should suspect the mass is:

• A. Retained placental tissue.
• B. A second fetus.
• C. Her uterus.
• D. A tumor.

Answer: (C)

Postpartum hemorrhage from uterine atony is the key idea. After the placenta separates, the uterus must contract firmly to compress the blood vessels and stop bleeding. If it fails to contract, the uterus remains enlarged and soft — a boggy, grapefruit-sized mass that’s often tender when palpated in the lower abdomen. That palpable mass is the uterus itself, still large because it hasn’t tightened down. Retained placental tissue can cause ongoing bleeding too, but it usually presents with tissue within the uterus rather than an obviously enlarged, tender exterior mass; a second fetus isn’t plausible right after delivery, and a tumor wouldn’t present acutely in this postpartum context.