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Difficulty: MediumLabor, Delivery, and Puerperium

A 28-year-old primigravida at 4141 weeks gestation is admitted to the labor and delivery unit for induction of labor. Following cervical ripening, a continuous intravenous oxytocin infusion is started. Twelve hours later, the patient reports intense and continuous abdominal pain. Her temperature is 37.2∘C37.2^\circ\text{C} (99.0∘F99.0^\circ\text{F}), blood pressure is 122/78 mm Hg122/78\text{ mm Hg}, and pulse is 92/min92/\text{min}. A sterile vaginal examination reveals the cervix is 6 cm6\text{ cm} dilated and 90%90\% effaced, with the fetal vertex at 00 station. The external tocodynamometer records 77 uterine contractions in a 1010-minute period, averaged over the last 3030 minutes. The continuous fetal heart rate tracing demonstrates a baseline of 145/min145/\text{min}, moderate variability, and symmetric decreases in the heart rate that begin after the peak of each contraction and slowly return to baseline after the contraction ends. Repositioning the patient to the left lateral decubitus position and providing a rapid intravenous fluid bolus do not resolve the fetal heart rate findings. Which of the following is the most appropriate next step in management?

  1. Discontinue the oxytocin infusionAnswer
  2. B
    Transfer to the operating room for cesarean delivery
  3. C
    Inject a dose of subcutaneous terbutaline
  4. D
    Begin an intra-amniotic infusion of isotonic saline
  5. E
    Perform artificial rupture of the amniotic membranes

Answer

The correct answer is to discontinue the oxytocin infusion to resolve the uterine tachysystole and improve uteroplacental blood flow.
This patient is experiencing uterine tachysystole, defined as >5>5 contractions in a 1010-minute period averaged over 3030 minutes. The excessively frequent contractions prevent adequate relaxation of the myometrium, impeding the restoration of uteroplacental blood flow between contractions. This uteroplacental insufficiency is clinically manifesting as recurrent late decelerations on the fetal heart rate monitor. The initial management for tachysystole with a Category II fetal heart rate tracing includes supportive measures such as lateral maternal repositioning and intravenous fluid boluses. Because this patient's tracing has not improved with these initial interventions and she is currently receiving an oxytocin infusion, the most direct, required next step is to immediately discontinue the oxytocin. This will reduce contraction frequency and allow uteroplacental perfusion to recover.

Step-by-Step Solution

1
Analyze the uterine activity from the tocodynamometer.
The patient is having 7 contractions per 10 minutes.
Uterine tachysystole is defined as more than 5 contractions in a 10-minute window, which can compromise blood flow to the fetus.
2
Interpret the fetal heart rate (FHR) tracing.
The FHR shows a normal baseline and moderate variability, but recurrent late decelerations are present.
Late decelerations are a sign of uteroplacental insufficiency, which in this case is secondary to the excessive uterine contractions.
3
Determine the appropriate order of intrauterine resuscitation interventions.
Since maternal repositioning and fluid bolus failed, the oxytocin must be stopped.
When tachysystole is iatrogenic, discontinuing the uterotonic agent is the most direct and necessary next step before proceeding to tocolytics or surgery.

Key Concept

Management of oxytocin-induced uterine tachysystole with abnormal fetal heart rate tracing requires immediate discontinuation of the oxytocin infusion.
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Topics

Labor, Delivery, and Puerperium

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