What is the most appropriate next step in management for a 24-year-old nulliparous woman at 34 weeks' gestation presenting with decreased fetal movement?

Management of Decreased Fetal Movement at 34 Weeks' Gestation

A non-stress test (NST) is the most appropriate next step in management for this 24-year-old nulliparous woman at 34 weeks' gestation presenting with decreased fetal movement. 1

Rationale for Non-Stress Test as First-Line Assessment

Decreased fetal movement is a significant clinical concern that requires prompt evaluation as it may indicate fetal compromise. The management approach should be systematic:

1. Non-stress test (NST) as initial assessment:

   • The Society for Maternal-Fetal Medicine guidelines recommend cardiotocography testing (NST) as part of the initial evaluation for suspected fetal compromise 2
   • NST provides immediate information about current fetal status and well-being 2
   • It allows for rapid assessment of fetal heart rate patterns and reactivity, which correlate with fetal oxygenation status

2. Why NST before other options:

   • NST is non-invasive and provides real-time information about fetal status
   • It can quickly identify fetuses that may be experiencing hypoxia or distress
   • Abnormal NST results would guide subsequent management decisions

Management Algorithm for Decreased Fetal Movement

Step 1: Initial Assessment with NST

• Perform NST immediately to evaluate fetal heart rate patterns and reactivity
• A reactive NST (showing at least two accelerations of ≥15 beats per minute lasting ≥15 seconds within a 20-minute period) is reassuring

Step 2: Based on NST Results

• If NST is reactive (normal):

  • Proceed with additional testing as needed (biophysical profile, umbilical artery Doppler)
  • Consider outpatient follow-up with continued fetal movement monitoring

• If NST is non-reactive or shows concerning patterns:

  • Proceed immediately to biophysical profile (BPP)
  • Initiate intrauterine resuscitation measures if needed 2
  • Consider umbilical artery Doppler studies to assess placental function 2

Step 3: Additional Management Based on Complete Assessment

• If evidence of fetal growth restriction is found:
  • Serial umbilical artery Doppler assessment should be performed 2
  • Weekly cardiotocography testing is recommended for FGR without absent/reversed end-diastolic velocity 2
  • Consider delivery timing based on Doppler findings and gestational age 2

Why Other Options Are Not First-Line

1. Biophysical profile (BPP):

   • While valuable, BPP is more time-consuming and typically performed after an abnormal or non-reassuring NST
   • BPP is appropriate as a follow-up test but not as the initial assessment for decreased fetal movement 2

2. Pelvic examination:

   • Not indicated as initial management for decreased fetal movement without signs of labor, vaginal bleeding, or rupture of membranes
   • Would not provide information about fetal well-being

3. Vibro-acoustic stimulation:

   • Used as an adjunct to NST, not as a standalone initial test
   • Can be employed during NST to elicit fetal response if initial tracing is non-reactive 2

Important Considerations

• Decreased fetal movement is associated with increased risk of stillbirth, fetal growth restriction, and adverse outcomes 1
• If NST shows abnormalities, prompt escalation to comprehensive fetal assessment is necessary
• At 34 weeks' gestation, antenatal corticosteroids should be considered if delivery appears imminent based on concerning fetal assessment 2, 3
• Documentation of maternal perception of decreased fetal movement is important as it has been shown to be a significant indicator of potential fetal compromise 4, 5

By following this evidence-based approach starting with NST, clinicians can efficiently evaluate fetal well-being and determine appropriate next steps for management in cases of decreased fetal movement.