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A 39-year-old woman, gravida 1 para 0, at 38 weeks gestation comes to the hospital for induction of labor. The patient has a history of hypertension for which she takes nifedipine. She also has a history of asthma for which she takes albuterol as needed, but she has had no recent exacerbations. On admission, blood pressure is 140/80 mm Hg and pulse is 94/min. After a prolonged labor, the patient delivers a 4.1-kg (9-lb) boy via forceps-assisted vaginal delivery and develops a third-degree perineal laceration. During delivery of the placenta, excessive traction is placed on the cord, causing it to avulse, and the placenta is manually extracted. Ultrasound after the extraction reveals a thin endometrial stripe. The perineal laceration is repaired in layers. Sixty minutes after delivery, the patient's perineal pad becomes soaked with blood. On bimanual uterine examination, 1,000 mL of clotted blood is expressed from the lower uterine segment. The uterus is soft and 4 cm above the umbilicus after expression of the clots.
Item 1 of 2
Which of the following is the most likely cause of this patient's bleeding?
Postpartum uterine atony | |
Risk factors |
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Clinical features |
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Interventions |
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This patient with heavy bleeding and blood clots in the lower uterine segment has uterine atony, the most common cause of postpartum hemorrhage (PPH) within 24 hours of delivery. Uterine atony occurs due to insufficient uterine contractility, resulting in the inability of the uterus to clamp down on bleeding placental bed vessels. Risk factors include uterine overdistension (often associated with fetal macrosomia [weight ≥4 kg]), uterine fatigue (eg, prolonged induction of labor), and operative vaginal delivery (eg, forceps-assisted), all of which are present in this patient.
Normally during the immediate postpartum period, contractions increase uterine tone, causing a firm uterine fundus to be palpable at or below the umbilicus. In contrast, patients with uterine atony have a soft, boggy, enlarged uterus with the fundus palpable above the umbilicus because of decreased uterine tone. Some patients may not have an immediate PPH, such as this patient whose bleeding was identified 60 minutes after delivery, because blood can gradually accumulate in the lower uterine segment (the least contractile portion of the uterus).
(Choice A) Cervical lacerations can occur due to trauma from operative vaginal delivery, particularly forceps-assisted vaginal delivery. Cervical lacerations may cause PPH, but the onset is typically immediate rather than 60 minutes after fetal delivery. In addition, there is no associated uterine bogginess or enlargement.
(Choice B) Although PPH can cause dilutional coagulopathy, this patient's blood is clotting, making coagulopathy unlikely.
(Choice C) This patient had cord avulsion that necessitated manual placental extraction, which risks leaving behind placental fragments that can cause PPH. However, a retained placenta is unlikely in this patient with an ultrasound revealing a thin endometrial stripe (suggesting an empty intrauterine cavity).
(Choice E) Uterine inversion can occur due to excessive traction on the umbilical cord with an adherent placenta, causing the uterine fundus to invert and prolapse. Although it can cause PPH, patients typically have severe abdominal pain, a smooth mass protruding from the cervix or vagina, and no palpable uterine fundus.
Educational objective:
The most common cause of postpartum hemorrhage within 24 hours of delivery is uterine atony, which results from inadequate uterine contractility and inability to compress the placental bed blood vessels. Patients typically have a soft, boggy, enlarged uterus with blood clots in the lower uterine segment and profuse vaginal bleeding. Risk factors include fetal macrosomia, prolonged induction of labor, and operative vaginal delivery.