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Difficulty: MediumObstetric Complications

A 25-year-old nulliparous woman at 40 weeks and 2 days gestation is admitted to the labor and delivery unit for induction of labor. An intravenous oxytocin infusion is initiated. Six hours later, the patient is reporting significant pain but is coping well with epidural anesthesia. Her temperature is 37.4°C (99.3°F), blood pressure is 118/76 mmHg, and pulse is 92/min. The cervix is 6 cm dilated, 90% effaced, and the fetal head is at 0 station. Review of the external tocodynamometer over the past 30 minutes shows 7 uterine contractions per 10-minute window, with each contraction lasting 60 to 80 seconds. The continuous fetal heart rate monitor demonstrates a baseline of 130/min, minimal variability, and visually apparent, gradual decreases in the fetal heart rate that nadir after the peak of the contractions and return to baseline after the contractions conclude. The patient's hemoglobin is 10.8 g/dL with a normal mean corpuscular volume. Which of the following is the most appropriate next step in management?

  1. Discontinue the intravenous oxytocin infusionAnswer
  2. B
    Proceed to emergent cesarean delivery
  3. C
    Initiate a transcervical amnioinfusion
  4. D
    Administer intravenous ampicillin and gentamicin
  5. E
    Provide reassurance and maintain the current infusion rate

Answer

Discontinue the intravenous oxytocin infusion
The correct answer is to discontinue the intravenous oxytocin infusion. This patient is experiencing uterine tachysystole, defined as more than 5 contractions in a 10-minute window averaged over 30 minutes. Uterine contractions temporarily interrupt blood flow to the intervillous space. When contractions are too frequent, the placenta does not have adequate time to reoxygenate between contractions, leading to uteroplacental insufficiency. This is manifesting on the fetal monitor as late decelerations (gradual decreases in fetal heart rate that begin after the peak of the contraction) and minimal variability. The immediate next step in management is intrauterine resuscitation to improve fetal oxygenation. The most direct and effective initial action when a patient is receiving an induction agent is to discontinue the oxytocin.

Step-by-Step Solution

1
Analyze the maternal contraction pattern on the tocodynamometer.
The tracing shows 7 contractions per 10 minutes.
To identify uterine tachysystole, which is defined as more than 5 contractions in a 10-minute period averaged over 30 minutes.
2
Evaluate the fetal heart rate tracing.
The tracing shows minimal variability and gradual decreases that nadir after the peak of the contraction.
To identify late decelerations, which indicate uteroplacental insufficiency secondary to the tachysystole.
3
Determine the most appropriate initial intervention.
Discontinue the oxytocin infusion.
Intrauterine resuscitation should begin immediately by removing the offending uterotonic agent causing the hyperstimulation.

Key Concept

Uterine tachysystole with late decelerations requires immediate intrauterine resuscitation, starting with the discontinuation of uterotonic agents like oxytocin.
Estimated Time:1m 30s
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Topics

Obstetric Complications

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