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Difficulty: EasyLabor, Delivery, and Puerperium

A 2929-year-old multiparous woman at 4040 weeks gestation is currently on the labor ward receiving an oxytocin infusion to augment active labor. Her pregnancy history includes 11 prior uncomplicated vaginal delivery. Vital signs are within normal limits. The continuous electronic fetal monitor displays a baseline heart rate of 145145/min with minimal variability. Upon review of the tracing, the physician notes recurrent, smooth, gradual decreases in the fetal heart rate. The lowest point of each deceleration consistently occurs after the peak of the corresponding uterine contraction, and the heart rate returns to baseline after the contraction has finished. Cervical examination reveals 66 cm dilation and 80%80\% effacement with the fetal vertex at 00 station. Which of the following is the most appropriate next step in management?

  1. Discontinue the oxytocin infusion and reposition the patientAnswer
  2. B
    Proceed to immediate cesarean delivery
  3. C
    Continue the current management and monitor closely
  4. D
    Initiate an amnioinfusion with normal saline
  5. E
    Perform an immediate operative vaginal delivery

Answer

Discontinue the oxytocin infusion and reposition the patient
The patient is experiencing recurrent late decelerations, characterized by a smooth, gradual decrease in the fetal heart rate that begins after the peak of the uterine contraction. This pattern indicates uteroplacental insufficiency, which can result in transient or prolonged fetal hypoxia. The most appropriate initial step in management is intrauterine resuscitation. This involves discontinuing any uterotonic agents (such as oxytocin) to reduce uterine activity, repositioning the patient to the left lateral decubitus position to relieve aortocaval compression and increase venous return, administering an intravenous fluid bolus, and potentially providing supplemental oxygen. These steps maximize placental blood flow and fetal oxygenation.

Step-by-Step Solution

1
Analyze the fetal heart rate tracing described in the clinical vignette.
The tracing shows gradual decreases in the fetal heart rate where the nadir occurs after the peak of the contraction. This defines late decelerations.
Identifying the specific pattern of deceleration is essential to determine the underlying pathophysiology and subsequent management.
2
Determine the etiology of the identified deceleration pattern.
Late decelerations are caused by uteroplacental insufficiency, which can compromise fetal oxygenation.
Understanding the underlying cause directs the clinician toward interventions that restore blood flow and oxygen delivery to the fetus.
3
Select the most appropriate initial management step.
The first required step is intrauterine resuscitation, primarily by stopping oxytocin and repositioning the mother.
These measures immediately reduce uterine vascular resistance and relieve aortocaval compression, improving uteroplacental perfusion before invasive measures are considered.

Key Concept

Recurrent late decelerations indicate uteroplacental insufficiency and require immediate intrauterine resuscitation, starting with maternal repositioning and discontinuation of uterotonics.
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Topics

Labor, Delivery, and Puerperium

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