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Difficulty: HardLabor, Delivery, and Puerperium

A 28-year-old primigravida at 40 weeks gestation is admitted to the labor and delivery unit in spontaneous labor. Her prenatal course has been uncomplicated. Her vital signs are within normal limits. Cervical examination reveals dilation to 5 cm, 90% effacement, and 0 station. Epidural analgesia is providing adequate pain relief.

Continuous fetal heart rate monitoring demonstrates a baseline of 140/min, minimal variability, and no spontaneous accelerations. Over the past 45 minutes, there are intermittent decelerations occurring with approximately 30% of contractions. These decelerations begin after the peak of the contraction, take more than 30 seconds to reach their nadir, and slowly return to baseline.

In response, the patient is repositioned to the left lateral decubitus position, administered a 500-mL intravenous fluid bolus, and given supplemental oxygen. Thirty minutes later, her contractions are occurring every 3 to 4 minutes. The fetal heart rate tracing remains unchanged, with persistent minimal variability and intermittent late decelerations.

Which of the following is the most appropriate next step in management?

  1. Digital fetal scalp stimulationAnswer
  2. B
    Immediate cesarean delivery
  3. C
    Administration of subcutaneous terbutaline
  4. D
    Transcervical amnioinfusion
  5. E
    Continued expectant management

Answer

Digital fetal scalp stimulation
The patient has a Category II fetal heart rate tracing characterized by minimal variability and intermittent late decelerations (occurring with <50% of contractions). Initial intrauterine resuscitation (maternal repositioning, IV fluids, oxygen) did not improve the tracing. To evaluate for potential fetal acidemia, an acid-base assessment is indicated. Digital fetal scalp stimulation is a safe, noninvasive method used to elicit a fetal heart rate acceleration. The presence of an acceleration (even in the setting of minimal variability) reliably excludes fetal acidemia, whereas the absence of an acceleration in this context may prompt consideration for operative delivery.

Step-by-Step Solution

1
Analyze the fetal heart rate (FHR) tracing characteristics.
The tracing shows a normal baseline, minimal variability, no accelerations, and intermittent late decelerations, classifying it as a Category II tracing.
Accurate interpretation of the FHR tracing is required to determine the level of risk for fetal acidemia.
2
Evaluate the response to initial intrauterine resuscitation.
Maternal repositioning, IV fluids, and oxygen were administered, but the tracing remained unchanged after 30 minutes.
Initial conservative measures aim to improve uteroplacental blood flow; failure to improve necessitates further diagnostic or therapeutic action.
3
Determine the next appropriate clinical step based on ACOG algorithms for Category II tracings.
Because variability remains minimal and no accelerations are present, assessing fetal acid-base status is required.
Persistent minimal variability with late decelerations is highly concerning for developing fetal acidemia. Eliciting an acceleration via scalp stimulation reliably confirms a normal fetal pH (> 7.20).
4
Select the correct intervention from the options.
Digital fetal scalp stimulation is selected as the noninvasive method of choice.
It safely distinguishes a compensated fetus (which will accelerate) from an acidemic fetus (which will not), guiding the decision between continuing labor and proceeding to operative delivery.

Key Concept

Management of Category II fetal heart rate tracings with persistent minimal variability and late decelerations requires assessment of fetal acid-base status, typically via digital fetal scalp stimulation, after initial intrauterine resuscitation fails.
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Topics

Labor, Delivery, and Puerperium

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