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Difficulty: MediumLabor, Delivery, and Puerperium

A gravida 1 para 0 at 39 weeks and 5 days of gestation is admitted to the labor and delivery unit in active labor. Her prenatal course was uncomplicated. Her temperature is 37.1°C (98.8°F), blood pressure is 122/78 mm Hg, and pulse is 88/min. The estimated fetal weight is 3,200 g (7 lb 1 oz). Cervical examination shows 6 cm dilation, 90% effacement, and 0 station. Spontaneous rupture of membranes occurred 3 hours ago, revealing clear amniotic fluid. Uterine contractions are occurring every 3 to 4 minutes and palpate as strong. Continuous external fetal monitoring demonstrates a baseline heart rate of 145/min with moderate variability. There are recurrent, abrupt decreases in the fetal heart rate to 90/min that last for 45 to 60 seconds before rapidly returning to baseline; these decreases occur with almost every contraction. Maternal repositioning to the left lateral decubitus position and administration of an intravenous fluid bolus were performed 15 minutes ago, but the fetal heart rate pattern remains unchanged. Which of the following is the most appropriate next step in management?

  1. Initiation of transcervical amnioinfusionAnswer
  2. B
    Emergent cesarean delivery
  3. C
    Application of fetal scalp forceps for extraction
  4. D
    Administration of subcutaneous terbutaline
  5. E
    Administration of intravenous broad-spectrum antibiotics

Answer

Initiation of transcervical amnioinfusion
The patient's fetal heart rate tracing demonstrates recurrent variable decelerations, characterized by abrupt decreases in the fetal heart rate that coincide with contractions. These are typically caused by umbilical cord compression, which is common after the rupture of membranes due to the loss of cushioning amniotic fluid. Initial management includes maternal repositioning (to shift the fetus off the cord) and fluid administration. Because these initial measures have failed, the next best step is transcervical amnioinfusion. Amnioinfusion involves instilling isotonic fluid into the uterine cavity via an intrauterine pressure catheter to artificially restore the amniotic fluid volume, thereby relieving cord compression and reducing the frequency and severity of variable decelerations.

Step-by-Step Solution

1
Interpret the fetal heart rate tracing based on the provided description.
The tracing shows recurrent variable decelerations (abrupt decreases in heart rate associated with contractions) with a normal baseline and moderate variability.
Accurate interpretation of the fetal heart rate tracing is required to determine the underlying pathophysiology, which in this case is umbilical cord compression.
2
Evaluate the patient's response to initial interventions.
Initial intrauterine resuscitation (maternal repositioning and fluid bolus) has already been attempted but failed to resolve the decelerations.
Management of Category II tracings follows a stepwise escalation protocol.
3
Select the next appropriate therapeutic intervention.
Amnioinfusion is indicated to restore amniotic fluid volume and cushion the umbilical cord.
Since the cervix is not fully dilated (precluding vaginal delivery) and the tracing still has moderate variability (reassuring acid-base status), an amnioinfusion is the safest and most effective next step to prevent progression to fetal acidemia.

Key Concept

Management of recurrent variable decelerations using amnioinfusion
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Topics

Labor, Delivery, and Puerperium

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