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Difficulty: EasyObstetric Complications

An 18-year-old nulliparous woman is admitted to the labor ward at 41 weeks of gestation for a scheduled labor induction. She is currently receiving a continuous intravenous infusion of oxytocin. A cervical examination reveals 6 cm of dilation and 80% effacement. The continuous external fetal monitor displays a baseline heart rate of 140/min with moderate variability. Over the last 20 minutes, the monitor reveals symmetric, gradual decreases in the fetal heart rate that begin after the peak of the uterine contractions and slowly return to baseline only after the contractions have completely ended. Maternal vital signs are temperature 37.1°C (98.8°F), blood pressure 118/76 mm Hg, pulse 88/min, and respirations 16/min. Which of the following is the most appropriate next step in management?

  1. A
    Observation and expectant management
  2. B
    Infusion of isotonic fluid into the amniotic cavity
  3. Discontinuation of the oxytocin infusionAnswer
  4. D
    Emergent surgical delivery
  5. E
    Artificial rupture of the amniotic membranes

Answer

Discontinuation of the oxytocin infusion
The fetal heart rate tracing described in the scenario is classic for late decelerations, which are characterized by a gradual decrease in the fetal heart rate with a nadir that occurs after the peak of the uterine contraction. Late decelerations are a concerning sign of uteroplacental insufficiency, which can lead to progressive fetal hypoxia and acidemia if left uncorrected. The initial management consists of intrauterine resuscitation aimed at improving placental blood flow and fetal oxygenation. The standard steps for intrauterine resuscitation include maternal repositioning (e.g., left lateral decubitus), administration of supplemental oxygen, intravenous fluid boluses, and the immediate discontinuation of any uterotonic agents. Therefore, stopping the oxytocin infusion is a critical next step. This action decreases uterine contraction frequency and intensity, allowing for maximum restoration of uteroplacental perfusion between contractions.

Step-by-Step Solution

1
Interpret the fetal heart rate tracing abnormalities.
The tracing shows symmetric, gradual decreases in heart rate with nadirs occurring after the peaks of the contractions, which defines late decelerations.
Accurate interpretation of the fetal monitor is the essential first step in determining fetal well-being.
2
Determine the underlying pathophysiology of the identified decelerations.
Late decelerations are caused by uteroplacental insufficiency, indicating transient fetal hypoxia during contractions.
Understanding the etiology (decreased placental perfusion) directs the clinician toward the appropriate corrective interventions.
3
Select the most appropriate initial resuscitative intervention.
Discontinuation of the oxytocin infusion is chosen as the immediate next step.
Stopping the uterotonic agent reduces the frequency and intensity of uterine contractions, directly addressing the uteroplacental insufficiency and improving fetal oxygenation.

Key Concept

Management of late fetal heart rate decelerations with intrauterine resuscitative measures.
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Topics

Obstetric Complications

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