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Difficulty: Very hardObstetric Complications

A 24-year-old woman, gravida 2, para 1, at 40 weeks gestation is admitted to the labor and delivery unit for an elective induction of labor. A continuous intravenous oxytocin infusion was started 12 hours ago. Her pain is well controlled with a functioning epidural catheter. A cervical examination reveals that she is 6 cm dilated, 90% effaced, and at -1 station. The fetal heart rate monitor demonstrates a baseline of 150/min, minimal variability, and symmetric, gradual decreases in the fetal heart rate that begin after the peak of the contractions and return to baseline after the contractions end. The tocodynamometer reveals 7 contractions every 10 minutes averaged over the last 30 minutes. The nursing staff immediately positions the patient in the left lateral decubitus position, administers a 500-mL intravenous fluid bolus of lactated Ringer solution, applies supplemental oxygen, and completely discontinues the oxytocin infusion. Reassessment 15 minutes later reveals that the contraction pattern remains at 7 contractions per 10 minutes, and the fetal heart rate tracing is unchanged. Which of the following is the most appropriate next step in management?

  1. Administer subcutaneous terbutalineAnswer
  2. B
    Perform an emergency cesarean delivery
  3. C
    Initiate transcervical amnioinfusion
  4. D
    Perform fetal scalp stimulation
  5. E
    Reassure the patient and continue continuous monitoring

Answer

Administer subcutaneous terbutaline
The correct action is administering subcutaneous terbutaline. This patient has uterine tachysystole (defined as more than 5 contractions per 10 minutes) leading to uteroplacental insufficiency, which is clinically manifested by late decelerations and minimal variability. The standard initial management for tachysystole includes maternal repositioning, intravenous fluid bolus, oxygen supplementation, and discontinuation of any uterotonic agents like oxytocin. When these initial steps fail to decrease the contraction frequency and improve the fetal heart tracing, the immediate next step is the administration of a rapid-acting tocolytic agent, typically terbutaline. By relaxing the myometrium, terbutaline restores adequate blood flow to the intervillous space, facilitating fetal reoxygenation and frequently avoiding the need for an emergency surgical delivery.

Step-by-Step Solution

1
Analyze the fetal heart rate (FHR) tracing and contraction pattern.
The FHR shows recurrent late decelerations with minimal variability. The contraction pattern shows 7 contractions per 10 minutes.
Late decelerations indicate uteroplacental insufficiency, and >5 contractions in 10 minutes confirms the diagnosis of uterine tachysystole as the underlying cause.
2
Evaluate the response to initial intrauterine resuscitative measures.
Left lateral positioning, IV fluids, oxygen, and discontinuation of oxytocin were performed, but the tachysystole and late decelerations persisted after 15 minutes.
Initial conservative measures attempt to offload aortocaval compression, increase maternal blood volume, and remove exogenous uterotonics. Failure of these steps requires escalation of medical therapy.
3
Determine the definitive next step in the clinical algorithm.
Select administration of a tocolytic agent (subcutaneous terbutaline).
Tocolytics acutely relax the myometrium, increasing the time between contractions for placental reoxygenation, which often resolves the fetal distress and avoids immediate progression to cesarean delivery.

Key Concept

In patients with uterine tachysystole causing uteroplacental insufficiency (late decelerations) that does not resolve with initial resuscitative measures (including discontinuation of oxytocin), the next best step is the administration of a rapid-acting tocolytic agent such as subcutaneous terbutaline.
Estimated Time:1m 30s
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Topics

Obstetric Complications

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