Primary Postpartum Hemorrhage
A 30-year-old woman delivered twins vaginally at term 2 hours ago. She now has heavy vaginal bleeding of about 900 mL. Blood pressure is 95/55 mm Hg and pulse 112 beats/min. The uterine fundus is soft and palpable above the umbilicus. The placenta was delivered intact and no lacerations are seen. Which of the following is the most likely cause of her bleeding?
- A.Genital tract laceration
- B.Disseminated intravascular coagulopathy
- C.Uterine atonyCorrect
- D.Retained placental fragments
Explanation
Uterine atony causes roughly 70 to 80 % of primary postpartum hemorrhage and is strongly suggested here by a boggy fundus palpable above the umbilicus. Hemostasis after delivery depends on myometrial contraction mechanically compressing the spiral arterioles that supplied the placental bed, not on the clotting cascade. A twin gestation overdistends the uterus, impairing this contraction; other risk factors are polyhydramnios, macrosomia, grand multiparity, prolonged or augmented labour, and chorioamnionitis. The diagnosis is clinical: a soft, high fundus with brisk bleeding. Management proceeds in order with bimanual uterine massage and uterotonics (oxytocin first, then a second agent such as misoprostol, carboprost, or methylergometrine), then tamponade with an intrauterine balloon, then compression sutures, uterine artery ligation, or hysterectomy. Coagulopathy is unusual as the primary cause this early and typically follows massive bleeding, abruption, or amniotic fluid embolism; it presents with oozing from puncture sites and a firm uterus. Genital tract trauma bleeds continuously with a well-contracted uterus and requires inspection of the cervix and vagina under good light. Retained placental tissue is possible after a placenta reported as intact but usually causes later or persistent bleeding and is confirmed by ultrasound or manual exploration.
Why each option
- A.
- Lacerations bleed steadily despite a well-contracted uterus; none were found on inspection here.
- B.
- Coagulopathy usually follows massive hemorrhage, abruption, or amniotic fluid embolism, and presents with a firm uterus and oozing from puncture sites.
- C.
- Correct. A soft fundus above the umbilicus after a twin delivery is classic atony, the cause of most primary postpartum hemorrhage.
- D.
- Retained fragments cause delayed or persistent bleeding with a subinvoluted uterus; the placenta was delivered intact.
Reference: ACOG Practice Bulletin No. 183, Postpartum Hemorrhage, reaffirmed 2024
This is one of 3,306 questions in the MedBoardSA SMLE bank, with timed test mode, tutor mode, and progress tracking by topic.
Practise the full bank