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Question

Difficulty: HardLabor, Delivery, and Puerperium

A 29-year-old woman, gravida 2, para 1, is evaluated on the labor and delivery unit at 41 weeks gestation during an induction of labor for a postterm pregnancy. She is currently receiving continuous intravenous oxytocin. The most recent cervical examination demonstrates 5 cm dilation, 100% effacement, and -1 station. Uterine contractions are occurring every 3 minutes. Continuous fetal monitoring reveals a baseline heart rate of 135/min with minimal variability. Over the preceding 40 minutes, the fetal heart rate tracing demonstrates recurrent, gradual decreases in heart rate that initiate after the peak of each contraction, with the nadir occurring after the contraction has ceased. These heart rate decreases are present with more than half of the contractions. In response, the patient is repositioned to the left lateral decubitus position and administered an intravenous fluid bolus; however, the fetal monitor tracing remains unchanged following these interventions. Maternal vital signs are within normal limits. Which of the following is the most appropriate next step in management?

  1. A
    Emergency cesarean delivery
  2. B
    Initiation of transcervical amnioinfusion
  3. Discontinuation of the oxytocin infusionAnswer
  4. D
    Administration of subcutaneous terbutaline
  5. E
    Application of a fetal scalp electrode

Answer

Discontinuation of the oxytocin infusion
The patient is experiencing recurrent late decelerations, which indicate uteroplacental insufficiency. When initial resuscitative measures such as maternal repositioning and intravenous fluid boluses fail to improve the fetal heart rate tracing, any exogenous uterotonic agents (such as oxytocin) must be immediately discontinued. This action decreases uterine activity, thereby improving blood flow to the placenta and increasing fetal oxygenation. Only after exhausting these resuscitative measures should operative delivery be considered.

Step-by-Step Solution

1
Analyze the fetal heart rate tracing and clinical presentation.
The tracing reveals a baseline of 135/min, minimal variability, and gradual decelerations that reach their nadir after the peak of the contractions.
Identifying the specific type of deceleration is required to determine the underlying etiology.
2
Determine the pathophysiology of the decelerations.
Gradual decelerations with a delayed nadir correspond to late decelerations, which signify uteroplacental insufficiency.
Different decelerations require different targeted interventions (e.g., cord compression vs. uteroplacental insufficiency).
3
Evaluate the patient's current treatment and response.
The patient is on an oxytocin infusion. Initial resuscitative measures (left lateral positioning, intravenous fluids) have not resolved the late decelerations.
Before escalating to surgical delivery, all appropriate conservative intrauterine resuscitation steps must be exhausted.
4
Select the most appropriate next step in management.
The continuous oxytocin infusion must be discontinued.
Oxytocin stimulates uterine activity, which further compromises uteroplacental blood flow; stopping it is a critical and mandatory resuscitative measure.

Key Concept

The initial management of recurrent late fetal heart rate decelerations involves sequential intrauterine resuscitation, including maternal repositioning, intravenous fluid administration, and the immediate discontinuation of exogenous uterotonic agents such as oxytocin.
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Topics

Labor, Delivery, and Puerperium

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