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Difficulty: MediumLabor, Delivery, and Puerperium

A 24-year-old primigravida at 39 weeks gestation is admitted to the labor and delivery unit in active labor. Her pregnancy has been uncomplicated. Her temperature is 37.1°C (98.8°F), blood pressure is 118/76 mm Hg, and pulse is 82/min. Epidural anesthesia is placed for pain management, and an oxytocin infusion is started to augment labor. Two hours later, a cervical examination reveals that the cervix is 6 cm dilated, 90% effaced, and the fetal head is at -1 station. Uterine contractions are occurring every 2 to 3 minutes and palpate as strong. The fetal heart rate tracing shows a baseline of 140/min with moderate variability. There are recurrent, gradual decreases in the fetal heart rate that begin after the peak of each uterine contraction and return to baseline after the contraction ends. Which of the following is the most appropriate next step in management?

  1. A
    Proceed to emergent cesarean delivery
  2. B
    Perform an amnioinfusion
  3. Discontinue the oxytocin infusionAnswer
  4. D
    Perform a vacuum-assisted vaginal delivery
  5. E
    Continue current management and observe closely

Answer

The most appropriate next step is to discontinue the oxytocin infusion to improve uteroplacental blood flow.
The correct answer involves stopping the oxytocin infusion. The clinical vignette describes recurrent late decelerations, characterized by a gradual decrease in the fetal heart rate with a nadir occurring after the peak of the uterine contraction. Late decelerations are a sign of uteroplacental insufficiency. When uteroplacental blood flow is compromised, contractions further restrict oxygen delivery to the fetus, leading to transient fetal hypoxia and a reflex slowing of the heart rate. The initial management consists of intrauterine resuscitation measures designed to optimize placental perfusion. Discontinuing uterotonics (like oxytocin) is a critical first step because it decreases the frequency and intensity of uterine contractions, thereby improving uteroplacental blood flow. Other resuscitative measures include maternal repositioning (left lateral decubitus), administration of an intravenous fluid bolus, and supplemental oxygen.

Step-by-Step Solution

1
Interpret the fetal heart rate (FHR) tracing described in the vignette.
The tracing shows a normal baseline (140/min) and moderate variability, but with recurrent gradual decreases that begin after the contraction peak (late decelerations).
Accurate FHR interpretation is essential for diagnosing fetal compromise.
2
Identify the underlying pathophysiology of late decelerations.
Late decelerations are caused by uteroplacental insufficiency (decreased blood flow to the placenta during a contraction).
Understanding the cause guides the choice of therapeutic intervention.
3
Determine the next best step in management (intrauterine resuscitation).
The immediate priority is to stop oxytocin (to reduce contraction frequency and intensity), reposition the mother, and administer IV fluids and oxygen.
These conservative measures maximize placental perfusion and oxygen delivery to the fetus before resorting to operative delivery.

Key Concept

Recurrent late decelerations indicate uteroplacental insufficiency and must be managed immediately with intrauterine resuscitation, starting with the discontinuation of uterotonic agents like oxytocin.
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Topics

Labor, Delivery, and Puerperium

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