Fetus

Fetal Heart Tracing

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Fetal Heart Tracing, Fetal Heart Tones, Fetal Heart Rate, FHR, FHT, Continuous Electronic Fetal Monitoring, CEFM, Structured Intermittent Auscultation, SIA, Reassuring Fetal Heart Tracing, Non-reassuring Fetal Heart Tracing, Ominous Fetal Heart Tracing

  • Monitoring Options
  1. Continuous Electronic Fetal Monitoring (CEFM)
    1. Indicated in high risk pregnancy (see efficacy below)
    2. See Peripartum Risk to the Fetus
  2. Structured Intermittent Auscultation (SIA)
    1. Contraindications
      1. High risk maternal or fetal risk factors
      2. See Peripartum Risk to the Fetus
    2. Requirements
      1. Requires one-to-one nursing (q15 minute monitoring)
      2. Nurses must be skilled in FHR auscultation
      3. Nurses must be able to palpate contractions
      4. Non-reassuring findings require clinical evaluation
    3. Monitoring frequency
      1. Stage 1:
        1. Low Risk: Every 15-30 minutes
        2. High risk: Every 15 minutes
      2. Stage 2:
        1. Low Risk: Every 5-15 minutes
        2. High Risk: Every 5 min or after each contraction
      3. Other indications as needed
        1. Before and after procedure (e.g. AROM, IUPC)
        2. Before and after ambulation
        3. Before and after medication including anesthesia
        4. Abnormal uterine contraction pattern
        5. After vaginal examination
    4. Procedure
      1. Baseline Fetal Heart Rate (FHR)
        1. Auscultate and count FHR for 60 seconds
        2. Perform between contractions
      2. Fetal response to labor
        1. Auscultate and count FHR for 60 seconds
        2. Perform immediately after contraction
      3. Variability assessment
        1. See FHR Variability
  • Efficacy
  • Continuous Electronic Fetal Monitoring (CEFM)
  1. CEFM does not significantly improve fetal outcome
    1. Only measurable benefits
      1. Fewer Neonatal Seizures
      2. Good tracing is reassuring for good outcome
    2. No benefit in APGAR Scores
    3. No decrease in NICU admissions
    4. No change in perinatal death rate
    5. No reduction in Cerebral Palsy
      1. Non-reassuring tracing does not predict bad outcome
      2. False Positive Rate 99.8% if ominous tracing
        1. Late Decelerations
        2. Decreased variability
  2. CEFM increases the risk of surgical intervention
    1. Increases ceserean rate by 160%
    2. Increases operative Vaginal Delivery rate
  3. Consider Informed Consent for CEFM
    1. CEFM may be indicated in high risk pregnancies
    2. Consider intermittent monitoring if low risk
  4. References
    1. Luthy (1987) Obstet Gynecol 69(5):687-95 [PubMed]
    2. Leveno (1986) N Engl J Med 315(10):615-19 [PubMed]
  • Interpretation
  1. Based on either method of auscultation (CEFM or SIA)
    1. CEFM: Graphical tracing of FHR and contractions
    2. SIA: Baseline and 60 sec before/after contractions
  2. Approach Mnemonic: DR C BRAVADO
    1. Determine Risk
      1. See Peripartum Risk to the Fetus
      2. Assign low, medium or high risk (see prenatal risk factors)
    2. Contractions
      1. Assess rate, rhythm, frequency, duration, intensity, and resting tone
    3. Baseline RAte
      1. Bradycardia (<110 bpm)
      2. Tachycardia (>160 bpm)
      3. Rising baseline
    4. Variability
      1. Absent or minimal variability suggests CNS Activity
    5. Accelerations
      1. Reassuring accelerations are >15 bpm above baseline for 15 seconds (if preterm >10 bpm for 10 seconds)
    6. Decelerations
      1. See Variable Decelerations
      2. See Late Decelerations
    7. Overall Assessment
      1. See Nonreassuring Fetal Status
  • Signs
  • Reassuring
  1. Normal baseline (120-160)
  2. Moderate Fetal Bradycardia (100-120), good variability
  3. Good beat-to-beat variability (STV)
  4. Accelerations
    1. Heart Rate increases by 15-25 bpm over baseline
    2. Increase persists for 15-25 seconds
  5. Early Decelerations
    1. Suggests head compression with contraction
  6. Mild Variable Decelerations
  • Signs
  • Non-Reassuring
  1. Fetal Tachycardia (>160)
  2. Moderate Fetal Bradycardia (100-120), lost variability
  3. Absent beat-to-beat variability (STV)
  4. Marked Fetal Bradycardia (90-100 bpm)
  5. Moderate Variable Decelerations
  6. Variable Decelerations
  7. Early Decelerations and slow return baseline
  • Signs
  • Ominous
  1. Fetal Tachycardia with loss of variability
  2. Prolonged marked Fetal Bradycardia (<90 bpm)
  3. Late Decelerations
  4. Severe Variable Decelerations
    1. Fetal Heart Rate drops below 70 beats per minute
    2. Deceleration persists for 1 minute or more