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Difficulty: MediumLabor, Delivery, and Puerperium

A 29-year-old primigravida at 41 weeks gestation is admitted to the labor and delivery unit for induction of labor due to postterm pregnancy. She is currently receiving a continuous intravenous oxytocin infusion. Her vital signs are temperature 37.0°C (98.6°F), blood pressure 122/78 mmHg, and heart rate 88/min. Cervical examination reveals 7 cm dilation, 100% effacement, and the fetal vertex is at 0 station. Uterine contractions are occurring every 3 minutes and palpate firm. The continuous fetal heart rate monitor shows a baseline of 140/min with minimal variability. There are gradual, symmetric decreases in the fetal heart rate that reach their nadir after the peak of the uterine contractions and return to baseline after the contractions end. These decelerations occur with more than 50% of the contractions. Which of the following is the most appropriate next step in management?

  1. Discontinue the intravenous oxytocin infusionAnswer
  2. B
    Perform a prophylactic amnioinfusion
  3. C
    Proceed immediately to cesarean delivery
  4. D
    Administer intravenous terbutaline
  5. E
    Apply a fetal scalp electrode

Answer

Discontinue the intravenous oxytocin infusion
The patient's fetal heart rate tracing demonstrates recurrent late decelerations (nadirs occurring after the peak of contractions), which are a sign of uteroplacental insufficiency and fetal hypoxia. The most appropriate initial step in management is intrauterine resuscitation to improve uteroplacental blood flow. Essential components of this resuscitation include maternal repositioning (e.g., left lateral decubitus), administering an intravenous fluid bolus, providing supplemental oxygen, and discontinuing any uterotonic agents. Because this patient is actively receiving an oxytocin infusion, immediately discontinuing the oxytocin is a critical first step to decrease uterine stimulation, thereby maximizing placental perfusion and oxygen delivery to the fetus.

Step-by-Step Solution

1
Analyze the fetal heart rate (FHR) tracing described in the clinical vignette.
The FHR shows a baseline of 140/min, minimal variability, and gradual decelerations with nadirs occurring after the peaks of contractions. These are classic late decelerations.
Accurate identification of the FHR deceleration pattern is required to determine the underlying pathophysiology.
2
Determine the etiology of late decelerations.
Late decelerations indicate uteroplacental insufficiency, meaning the fetus is experiencing transient hypoxemia during uterine contractions.
Understanding the cause guides the appropriate therapeutic intervention.
3
Select the initial management for recurrent late decelerations in a patient receiving labor induction.
The immediate goal is to improve placental blood flow. Stopping the oxytocin infusion reduces uterine activity, allowing for better placental perfusion.
Intrauterine resuscitation must be initiated before considering invasive or operative interventions.

Key Concept

Recurrent late decelerations indicate uteroplacental insufficiency and must be managed initially with intrauterine resuscitation, which includes maternal repositioning, fluid administration, oxygen, and discontinuing uterotonic agents like oxytocin.
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Topics

Labor, Delivery, and Puerperium

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