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Difficulty: MediumLabor, Delivery, and Puerperium

A woman at 40 weeks gestation, gravida 1, para 0, is undergoing labor induction for oligohydramnios. She is 29 years of age. An oxytocin infusion was started six hours ago. She now complains of relentless, overlapping abdominal cramping. Maternal vital signs show a blood pressure of 118/72 mmHg, a heart rate of 84/min, and a temperature of 37.0°C (98.6°F). A review of the tocodynamometer reveals seven uterine contractions in the past ten minutes, lasting up to 90 seconds each. The fetal heart rate tracing demonstrates a baseline of 135/min, minimal variability, and recurrent gradual decreases in heart rate that reach their nadir after the peak of the contractions. Pelvic examination shows the cervix is 5 cm dilated, 80% effaced, and at -1 station. Which of the following is the most appropriate initial intervention?

  1. A
    Prepare the patient for an emergent cesarean delivery
  2. B
    Begin transcervical amnioinfusion with normal saline
  3. Discontinue the oxytocin infusion and assist the patient into a lateral positionAnswer
  4. D
    Administer a dose of subcutaneous terbutaline
  5. E
    Continue observation and reassure the patient

Answer

The most appropriate initial intervention is to discontinue the oxytocin infusion and assist the patient into a lateral position.
The patient is experiencing uterine tachysystole, defined as more than 5 contractions in 10 minutes averaged over a 30-minute window. This excessive uterine activity limits the time available for blood to flow through the intervillous space, leading to uteroplacental insufficiency, which manifests as late decelerations and minimal variability on the fetal monitor. The most appropriate initial step in intrauterine resuscitation is to stop the offending agent by discontinuing the oxytocin infusion. Assisting the patient into a lateral position relieves aortocaval compression and improves maternal cardiac output, further maximizing placental perfusion.

Step-by-Step Solution

1
Analyze the fetal heart rate and uterine activity tracing.
The tracing shows more than 5 contractions in 10 minutes (uterine tachysystole) accompanied by minimal variability and late decelerations.
Identifying the primary pathophysiologic problem of uteroplacental insufficiency due to excessive uterine contractions is required to determine the correct management.
2
Determine the immediate intervention for uterine tachysystole with nonreassuring fetal status.
The first step is to discontinue any uterotonic agents (oxytocin) and reposition the patient laterally.
Stopping the exogenous stimulus allows the uterus to relax, while lateral positioning increases venous return and cardiac output, rapidly restoring blood flow to the placenta.

Key Concept

The initial management of uterine tachysystole causing late decelerations is intrauterine resuscitation, which primarily involves discontinuing uterotonic agents and maternal repositioning.
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Topics

Labor, Delivery, and Puerperium

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