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Difficulty: EasyObstetric Complications

A 26-year-old primigravida at 39 weeks gestation is admitted to the hospital in spontaneous labor. Her pregnancy has been uncomplicated. Her cervix is 6 cm dilated and 90% effaced. The patient is receiving continuous external fetal monitoring. Over the last 30 minutes, the fetal heart rate baseline is 135/min with moderate variability. However, there are recurrent, symmetric decreases in the fetal heart rate that begin after the peak of each uterine contraction and return to baseline only after the contraction has completely finished. The patient's blood pressure is 120/80 mm Hg and her pulse is 85/min. Which of the following is the most appropriate initial step in the management of this patient?

  1. Placement of the patient in a lateral decubitus positionAnswer
  2. B
    Transfer to the operating room for surgical delivery
  3. C
    Start an intravenous oxytocin infusion
  4. D
    Instillation of sterile fluid into the uterine cavity
  5. E
    Continue continuous fetal monitoring without acute intervention

Answer

The most appropriate initial step is to place the patient in a lateral decubitus position.
The clinical scenario describes a patient in spontaneous labor whose fetus is experiencing late decelerations (decreases in fetal heart rate that begin after the peak of a contraction and recover after the contraction ends). Late decelerations indicate uteroplacental insufficiency. The first-line management involves intrauterine resuscitation to optimize blood flow to the placenta. The most appropriate initial step is to reposition the mother (typically into the left lateral decubitus position) to alleviate aortocaval compression, which maximizes maternal cardiac output and consequently improves uteroplacental perfusion.

Step-by-Step Solution

1
Interpret the fetal heart rate tracing described in the vignette.
The tracing demonstrates recurrent late decelerations.
The decelerations have a gradual onset and return to baseline, consistently occurring after the peak of the uterine contractions.
2
Identify the underlying pathophysiology associated with this fetal heart rate pattern.
Late decelerations are a sign of transient uteroplacental insufficiency.
During the peak of a contraction, blood flow through the intervillous space is compromised, leading to temporary fetal hypoxia and a subsequent vagal response that slows the heart rate.
3
Determine the best initial management step.
Intrauterine resuscitation should be initiated immediately, starting with maternal repositioning.
Placing the mother in a lateral decubitus position relieves compression of the inferior vena cava by the gravid uterus, thereby improving maternal venous return, cardiac output, and uteroplacental perfusion.

Key Concept

The initial management of late decelerations consists of intrauterine resuscitation measures, prominently maternal lateral repositioning, to improve uteroplacental blood flow before considering operative delivery.
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Obstetric Complications

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