A 25-year-old primigravida at 37 weeks gestation is brought to the emergency department with constant, excruciating abdominal pain and sudden vaginal bleeding for the past 3 hours. The patient is Rh negative and received Rh(D) immunoglobulin at 28 weeks gestation. She has no chronic medical conditions and takes no medications. Blood pressure is 160/100 mm Hg and pulse is 118/min. Physical examination shows a firm and tender uterus. Speculum examination reveals a moderate amount of bleeding coming from an open cervical os. Fetal heart tracing shows a baseline of 105/min and no variability. Which of the following is the most likely cause of this patient's bleeding?
Abruptio placentae | |
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This patient in the third trimester with painful vaginal bleeding and a tender, firm uterus has a presentation consistent with abruptio placentae (ie, premature separation of the placenta from the uterus prior to fetal delivery). Abruptio placentae is associated with maternal hypertension, abdominal trauma, use of tobacco or cocaine (vasoconstrictors causing placental ischemia), and prior abruptio placentae.
Abruptio placentae occurs when maternal vessels rupture at the uteroplacental interface, causing intrauterine bleeding. This bleeding results in detachment of the placenta from the uterus, an increase in intrauterine pressure (eg, tender, distended uterus), and uterine irritability (eg, high-frequency, low-intensity contractions).
Some cases are self-limiting and contained, whereas others progress as the bleeding and placental separation continue. As the degree of placental separation increases, the risk of fetal compromise and mortality from hypoxia (eg, fetal bradycardia, minimal variability in the fetal heart rate tracing) also increases. Maternal complications include hemorrhage and disseminated intravascular coagulation. Acute abruptio placentae with active bleeding is an indication for delivery; the mode of delivery depends on both maternal and fetal stability.
(Choice A) Placenta accreta, direct attachment of the placental villi onto the myometrium, typically presents after delivery of the fetus with postpartum hemorrhage and inability to remove the placenta.
(Choice B) Uterine rupture, full-thickness disruption of the uterine wall, is associated with severe lower abdominal pain, vaginal bleeding, and fetal heart rate tracing abnormalities (eg, bradycardia). However, it typically occurs in patients with prior cesarean delivery (this patient is a primigravida) and typically has a uterus with palpable fetal parts, rather than uterine rigidity.
(Choice C) In vasa previa, the fetal vessels traverse the internal cervical os and are vulnerable to injury. However, patients typically have painless, rather than painful, vaginal bleeding.
(Choice D) Placenta previa, placental implantation over the cervix, typically presents in the third trimester with painless, rather than painful, vaginal bleeding and no uterine tenderness.
Educational objective:
Abruptio placentae, detachment of the placenta from the uterus prior to fetal delivery, presents with painful vaginal bleeding; a tender, firm uterus; and fetal heart rate abnormalities. Risk factors include abdominal trauma, maternal hypertension, and tobacco or cocaine use.