A 30-year-old woman, gravida 2 para 1, at 28 weeks gestation is evaluated in the emergency department for abdominal pain. The patient's pain is severe and began abruptly this morning in the midepigastrium, but now radiates to the entire abdomen. She has had nausea, but no vomiting, vision changes, headache, vaginal bleeding, or leakage of fluid. The patient has had no prenatal care during this pregnancy and her prior pregnancy ended in a cesarean delivery for failed induction of labor. She has a history of tobacco use, polysubstance drug use, and peptic ulcer disease. Temperature is 37 C (98.7 F), blood pressure is 150/94 mm Hg, and pulse is 118/min. The patient is in distress and is sweating profusely. The abdomen is soft and gravid. The uterine contour is smooth, rigid, and diffusely tender. Tocometry shows contractions every 1-2 minutes. Which of the following is the most likely cause of this patient's clinical presentation?
Abruptio placentae | |
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This patient with acute abdominal pain and a rigid, diffusely tender uterus likely has abruptio placentae, the premature separation of the placenta from the uterine wall. Although most patients develop vaginal bleeding, up to 20% have a concealed abruption, in which there is no visible bleeding. Patients with concealed abruptions typically have severe focal pain at the location of the placenta (such as this patient with mid-epigastric pain, which suggests a fundal placenta) that then progresses to diffuse uterine tenderness.
Risk factors for placental abruption include cocaine and tobacco use, as these substances are potent vasoconstrictors that readily cross the placenta and cause placental vasoconstriction and ischemia. The ischemia can then cause necrosis and hemorrhage at the uteroplacental interface, resulting in the subsequent detachment of the placenta from the uterine wall. As blood accumulates between the placenta and uterine wall, the intrauterine pressure increases (leading to a distended, tender uterus) and induces uterine irritability (triggering high-frequency contractions).
Severe cases of placental abruption can lead to maternal hemorrhage, fetal hypoxia and demise, and disseminated intravascular coagulation. Management is dependent on maternal and fetal stability.
(Choice A) Degeneration of a uterine leiomyoma may occur during pregnancy and present with focal pain. However, this patient's uterine contour is smooth, making this diagnosis less likely. In addition, fibroid degeneration does not typically cause uterine rigidity or high-frequency contractions.
(Choice B) Peptic ulcer perforation can present with sudden-onset, midepigastric pain that becomes diffuse. However, patients typically have peritoneal signs (eg, rebound, guarding) due to spillage of caustic gastric contents into the peritoneal cavity. This patient's abdomen is soft.
(Choice D) Uterine rupture can occur in patients with prior cesarean delivery due to separation of inelastic uterine scar tissue. Although patients have acute pain and uterine tenderness, their contractions are typically irregular and decreasing in intensity because ruptured myometrial muscle cannot contract in unison.
(Choice E) Uterine incarceration, entrapment of the uterus between the pubic symphysis and sacral promontory, is a rare condition typically occurring at <20 weeks gestation. Patients have constant lower abdominal pain that radiates to the back and urinary retention due to bladder obstruction.
Educational objective:
Abruptio placentae is the premature separation of the placenta from the uterine wall prior to fetal delivery. Patients typically have acute abdominal pain; a rigid, tender uterus; and high-frequency contractions. Risk factors include cocaine and tobacco use, which cause placental vasoconstriction, ischemia, and hemorrhage.