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Difficulty: HardObstetric Complications

A 32-year-old gravida 1 para 0 woman at 39 weeks gestation is admitted to the labor and delivery unit in active labor. Her prenatal course has been uncomplicated. Cervical examination reveals 6 cm dilation, 100% effacement, and 0 fetal station. The patient requests analgesia, and a lumbar epidural is placed. Fifteen minutes later, she reports the sudden onset of nausea and lightheadedness. Her temperature is 37.1°C (98.8°F), blood pressure is 80/45 mm Hg, and heart rate is 118/min. Prior to the epidural, continuous fetal monitoring demonstrated a baseline of 140/min with moderate variability and no decelerations. Currently, the monitor shows a sudden decrease in the fetal heart rate to 85/min that has persisted for the past 4 minutes. Uterine contractions are occurring every 3 to 4 minutes. The patient is immediately repositioned to the left lateral decubitus position and an intravenous normal saline bolus is initiated, but the maternal blood pressure remains low and the fetal heart rate remains at 85/min. Which of the following is the most appropriate next step in management?

  1. Administer intravenous ephedrineAnswer
  2. B
    Proceed to emergent Cesarean delivery
  3. C
    Perform a transcervical amnioinfusion
  4. D
    Administer subcutaneous terbutaline
  5. E
    Continue expectant observation of the fetal heart rate

Answer

Administer intravenous ephedrine
Epidural anesthesia frequently causes maternal hypotension due to sympathetic nerve blockade, which leads to systemic vasodilation and decreased venous return. This sudden drop in blood pressure significantly reduces uteroplacental perfusion, often manifesting as a fetal prolonged deceleration (a decrease in the fetal heart rate lasting between 2 and 10 minutes). Initial management includes placing the patient in the left lateral decubitus position to maximize venous return by relieving aortocaval compression and administering an intravenous fluid bolus. When these initial measures fail to rapidly correct the hemodynamics, administration of a vasopressor, such as intravenous ephedrine or phenylephrine, is the definitive next step. Vasopressors restore maternal vascular tone and blood pressure, thereby reestablishing placental blood flow and resolving fetal hypoxia.

Step-by-Step Solution

1
Diagnose the maternal complication.
The patient developed profound hypotension immediately following epidural placement.
Epidural anesthesia blocks sympathetic nerve fibers, causing systemic vasodilation, venous pooling, and decreased cardiac output.
2
Identify the cause of the fetal monitoring changes.
The fetal heart rate shows a prolonged deceleration (bradycardia).
Maternal hypotension directly decreases uteroplacental perfusion, leading to acute fetal hypoxia.
3
Evaluate the response to initial interventions.
Left lateral decubitus positioning (to relieve aortocaval compression) and intravenous fluids were insufficient to correct the blood pressure.
Initial mechanical and volume-based resuscitation did not adequately reverse the sympathetic blockade.
4
Determine the definitive next best step.
Administer a vasopressor (intravenous ephedrine or phenylephrine).
Pharmacologic vasoconstriction is required to rapidly restore maternal blood pressure, thereby restoring blood flow to the placenta and resolving the fetal deceleration.

Key Concept

Management of epidural-induced maternal hypotension and resulting fetal prolonged decelerations requires sequential intrauterine resuscitation: repositioning, intravenous fluids, and vasopressors.
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Topics

Obstetric Complications

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