Fetus

Variable Deceleration

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Variable Deceleration, FHR Variable Deceleration

  • See Also
  1. Fetal Assessment
  2. Fetal Testing Indications
  3. Fetal Heart Tracing
  4. Fetal Distress
  • Definitions
  1. Variable Deceleration
    1. Variable in relation to contraction
    2. Variable shape of deceleration
    3. Abrupt onset and return (steep slope of change)
      1. Contrast with other decelerations
    4. Associated with small acceleration
    5. Onset of Variable Deceleration to nadir < 30 seconds
    6. Heart Rate decrease >=15 bpm
    7. Variable Deceleration Duration 15 seconds to 2 minutes
  • Physiology
  1. Variable Decelerations are a result of cord compression
  2. Often benign if mild deceleration in active labor
  3. May represent uteroplacental insufficiency for some
  • Grading
  • Variable Decelerations
  1. Mild Variable Deceleration
    1. Variable Deceleration <30 seconds
    2. Fetal Heart Rate 80-120 bpm
    3. Fetal Heart Rate 70-120 bpm for <60 seconds
  2. Moderate Variable Deceleration
    1. Fetal Heart Rate <70 bpm for 30-60 seconds
    2. Fetal Heart Rate 70-120 bpm for >60 seconds
  3. Severe Variable Deceleration
    1. Fetal Heart Rate <70 bpm for >60 seconds
  • Interpretation
  1. More reassuring
    1. Acceleration just before variable ("Shoulder")
    2. Good baseline variability
    3. Rapid descent and recovery
  2. Non-Reassuring
    1. Repetitive severe decelerations
      1. Fetal Heart Rate <70 bpm for >60 seconds
      2. Occurs repeatedly over 20 minute observation
    2. Loss of "Shoulder" accelerations
    3. Loss of short-term variability
    4. Slow recovery from deceleration
    5. Baseline Tachycardia
  • References
  1. Bailey (2000) ALSO, E:1-13
  2. Gabbe (2002) Obstetrics, p. 395
  3. Arnold (2020) Am Fam Physician 102(3): 158-67 [PubMed]
  4. Rylander (2001) Clin Fam Pract 3(2):287-305 [PubMed]