A 37-year-old woman, gravida 4 para 0 aborta 3, comes to the labor and delivery department with painful contractions. She has had no prenatal care this pregnancy, but states she is at 37 weeks gestation based on a first-trimester ultrasound performed in the emergency department. The patient has had 3 elective pregnancy terminations with dilation and curettage. On physical examination, the cervix is 6 cm dilated and 90% effaced with the fetal head at +1 station. She dilates quickly to 10 cm and vaginally delivers a 4.5-kg (10-lb) male infant. Following delivery of the infant, the umbilical cord avulses from the placenta, necessitating manual extraction. The placenta is extracted in pieces, and the patient suddenly develops profuse vaginal bleeding. The uterus is firm, and the bleeding is unresponsive to uterine massage and uterotonic medications. Which of the following is the most likely cause of this patient's bleeding?
Placenta accreta | |
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D&C = dilation & curettage; US = ultrasound. | |
This patient with postpartum bleeding likely has placenta accreta, the abnormal attachment of placental villi to the uterine myometrium rather than the decidua basalis. This condition typically occurs in patients with endometrial scarring from prior uterine surgery (eg, dilation and curettage, cesarean delivery); the scarred areas do not undergo normal endometrial decidualization in early pregnancy. Therefore, fetal trophoblasts can implant directly onto the myometrium (rather than the endometrium) and form a morbidly adherent placenta.
Placenta accreta is usually diagnosed on routine second-trimester ultrasonography; however, in some cases (eg, limited prenatal care), diagnosis occurs after fetal delivery when there is difficulty detaching the placenta from the uterus. Excessive traction on the umbilical cord typically leads to cord avulsion. Attempts to remove the placenta (eg, manual extraction, sharp uterine curettage) are unsuccessful and cause profuse vaginal bleeding due to the disruption of highly vascular adhesions between the uterus and placenta. An emergency hysterectomy is typically required to minimize further maternal blood loss and achieve hemostasis.
(Choice A) Abruptio placentae is the premature detachment of the placenta from the uterus. It typically causes antepartum (not postpartum) bleeding associated with a painful, distended uterus and fetal heart rate abnormalities.
(Choice C) Placenta previa occurs due to abnormal placental implantation over the internal cervical os and is associated with prior uterine surgery (eg, cesarean delivery). In contrast to placenta accreta, placenta previa typically presents with painless antepartum bleeding.
(Choice D) Uterine atony occurs when the myometrium fails to contract after delivery, thereby allowing continued bleeding from the placental bed vessels. This diagnosis is unlikely in this patient with a firm uterus and bleeding that is unresponsive to uterine massage and uterotonic medications.
(Choice E) Uterine inversion can cause postpartum hemorrhage as the result of excessive traction on the umbilical cord and an abnormally adherent placenta. However, patients typically have severe abdominal pain and a smooth mass protruding from the cervix or vagina.
(Choice F) A vaginal hematoma occurs due to obstetric trauma and bleeding in the paravaginal space. Patients typically have a vaginal mass and concealed bleeding, not profuse vaginal bleeding.
Educational objective:
Placenta accreta is the abnormal attachment of placental villi to the uterine myometrium and can present with difficulty detaching the placenta after fetal delivery. Attempts at manual placental extraction are unsuccessful and can cause profuse vaginal bleeding. Treatment is typically with emergency hysterectomy.