Electronic Fetal Monitoring (EFM)

Introduction to Electronic Fetal Monitoring

• Electronic fetal monitoring (EFM) assesses fetal well-being during labor and delivery.
• These notes are useful for nurses, student nurses, and new graduates in labor and delivery.
• The Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN) offers EFM certification.
• EFM certification is available through the National Certification Corporation (NCC).

External Fetal Monitoring

• External fetal monitoring uses devices on the mother's abdomen to assess fetal heart rate and uterine contractions.
• An external monitor interprets the data.
• The display records data in real-time, either on paper or electronically.
• Continuous electronic fetal monitoring provides a continuous tracing of fetal heart rate and uterine activity.
• The EFM's graphic record is a legal document.
• Evidence-based practice indicates intermittent fetal monitoring is suitable for low-risk mothers.
• Continuous EFM use has increased in the last 30 years.
• Despite increased EFM use, there has been no significant decrease in neonatal morbidity (seizures, cerebral palsy).
• EFM's primary goal is to provide information about fetal oxygenation.
• EFM aids in preventing fetal injury caused by impaired oxygenation.
• EFM helps detect heart rate changes before they become prolonged and severe.
• Leopold's maneuvers are used to determine fetal position before applying EFM monitors.
• Fetal position aids in determining the monitors optimal placement.
  • This includes determining if the baby is head down (vertex) or bottom down (breech).
  • As well as determining on what side of the mother the baby's back is on.
• Mothers can often indicate where they feel the most fetal kicking, helping locate the fetal back for optimal monitor placement.
• The monitor works by assessing the condition through the abdomen.
• Straps are used to secure the monitors to the mother’s abdomen.
  • The monitor on the top of the uterus (fundus) detects uterine movement.
  • This monitor measures contraction frequency and duration, but not strength.
  • An ultrasound transducer with ultrasonic gel picks up fetal heart tones.
  • Cords may need adjustment to catch the heart rate.
  • Washcloths or belly bands can help achieve the correct monitoring angle.

Display Interpretation

• The upper portion of the EFM paper recording displays the fetal heart rate.
• The lower portion displays uterine activity (contractions).
• Vertical red lines represent one-minute intervals.
• Each small box between the red lines represents 10 seconds.
• On the fetal heart rate display, vertical scale increments represent 10 beats per minute (bpm).
• On the uterine activity display, vertical scale increments represent 5 mmHg (pressure).

Uterine Contraction Timing

• Frequency: Measured from the beginning of one contraction to the beginning of the next.
• Duration: Measured from the beginning to the end of a single contraction.
• Contractions are measured in seconds.
• Averages should be calculated over a 30-minute period.
• Tachysystole: More than five contractions in a 10-minute period, averaged over 30 minutes.
• Uterine contractions lasting longer than 120 seconds is also considered tachysystole.
• Reduced fetal blood flow occurs during uterine contractions.
• Nursing intervention is needed for uterine tachysystole to ensure adequate fetal recovery time.

Fetal Monitor Interpretation

• Interpretation uses the National Institute of Child Health and Human Development (NICHD) nomenclature for standardized communication.
• Steps to develop the NICHD Nomenclature:
  • Determine baseline fetal heart rate.
  • Determine fetal heart rate variability.
    • Assess if accelerations are present.
    • Assess if decelerations are present.
    • Determine the category the tracing falls into.
    • Assess if intervention is necessary.

Baseline Fetal Heart Rate

• Normal range: 110 to 160 bpm.
• Bradycardia: Heart rate below 110 bpm.
• Tachycardia: Heart rate above 160 bpm.
• Baseline determination requires a 20-minute tracing segment.
• An imaginary line representing the average heart rate, excluding accelerations and decelerations, is drawn.
• If the imaginary line is drawn through the tracing at the 135 bpm mark, the baseline would be reported as 135 bpm.

Fetal Heart Rate Variability

• Variability refers to beat-to-beat changes in the fetal heart rate.
• Absent variability: No changes in the heart rate; appears as a flat line.
• Minimal variability: 0 to 5 bpm change.
• Moderate variability: 6 to 25 bpm change.
• Marked variability: Greater than 25 bpm change.
• Oxygenation and variability are closely related; good variability often indicates good oxygenation.

Types of Variability Defined

• Minimal variability: Fetal heart rate changes less than half of the 10 bpm box.
• Moderate variability: Fetal heart rate changes from more than 6 to up to 25 bpm.
• Absent variability: Flat line; an ominous sign.
• Marked variability: Significant beat-to-beat changes, greater than 25 bpm.

Accelerations

• Accelerations: Abrupt increases in fetal heart rate.
• Defined as 15 bpm above the baseline for at least 15 seconds (15x15 rule).
• Accelerations are a positive sign indicating fetal reserve and adequate oxygenation.

Decelerations

• Decelerations: Decreases in fetal heart rate from the baseline.
• Variable decelerations
  • Abrupt, may have a V shape.
  • Decrease of 15 bpm for 15 seconds, but less than 2 minutes.
  • Not always associated with uterine contractions.
• Early decelerations
  • Occur at the same time as uterine contractions, mirroring the contraction pattern.
• Late decelerations
  • Begin after the start of the contraction, usually after the peak.
• Prolonged decelerations
  • Decrease in heart rate lasting more than two minutes.

Deceleration Types Defined

• Variable decelerations can be caused by cord compression.
• Early decelerations are caused by head compression.
• Late decelerations happen after the peak of the contraction.
  • Late decelerations are related to placental insufficiency.

VEAL CHOP Mnemonic

• A helpful tool for remembering the significance of decelerations:
  • V: Variable decelerations indicate Cord compression.
  • E: Early decelerations indicate Head compression.
  • A: Accelerations are Okay (indicate fetal well-being).
  • L: Late decelerations indicate Placental insufficiency.
• Variable decelerations are not necessarily an issue.
  • However, repetitive variable decelerations (more than 50% of the time) are concerning.
• Early decelerations due to head compression are benign.
• Late decelerations are not good; the baby is not getting enough oxygen or has no reserve.

Fetal Heart Rate Categories

• Reflect the overall assessment of fetal well-being based on heart rate patterns.
• Category I (Normal):
  • Baseline: 110-160 bpm.
  • Moderate variability.
  • Absent late or variable decelerations.
  • Early decelerations: Present or absent.
  • Accelerations: Present or absent.
• Category III (Abnormal):
  • Requires immediate intervention.
  • Bradycardia (under 110 bpm) or tachycardia (over 160 bpm).
  • Absent baseline variability.
  • Late or variable decelerations (recurrent).
  • More than two of these items necessitate immediate intervention.
• Expedite delivery if intervention is needed.
• Category II (Indeterminate):
  • Caution is required.
  • Includes patterns not meeting criteria for Category I or III.
  • May indicate fetal stress or potential compromise.
    • Good Category II:
      • May have tachycardia or bradycardia with at least minimal variability.
      • Minimal or absent baseline variability but no decelerations.
    • Ominous Category II:
      • Late or variable decelerations with minimal or moderate variability.
  • Prolonged deceleration (more than 2 minutes, less than 10 minutes).
  • Early decelerations: Absent or present.
  • Accelerations: Absent or present.

Visual Representation of Categories

• Category I baby exhibits moderate baseline variability with a normal baseline.
• Category II baby could be due to minimal variability with some variable decelerations.
• Category III baby will have absent variability with a late deceleration needing intervention.

Clinical Actions Based on Category

• Category I: Continue monitoring.
• Category II: Requires further evaluation and potential intervention to improve fetal oxygenation.
  • Consider discontinuing Pitocin (oxytocin) if in use.
  • Consider expediting delivery if symptoms persist or worsen.
• Category III: Requires prompt intervention to improve fetal oxygenation and expedite delivery.
  • Discontinue oxytocin.
  • Prepare for operative vaginal delivery or cesarean delivery.

Contraction Timing Review & Palpation

• Frequency: From the beginning of one contraction to the beginning of the next.
• Duration: From the beginning to the end of the same contraction.
• Assess contraction strength.
• Ask the patient about perceived contraction intensity.
• Place hand on the top of the fundus to measure strength subjectively.
  • Soft.
  • Moderate.
  • Firm.

Uterine Resuscitation

• Standard interventions to improve fetal oxygenation:
  • IV fluid bolus: Administer 500 mL of lactated Ringer's (LR) solution rapidly.
    • Pressure bag: Place pressure bag over the IV bag for rapid infusion.
  • Maternal position change:
    • Left lateral position is preferred.
    • Right lateral, hands and knees, or hips open with peanut ball can be used.
    • High Fowler's position (sitting upright) may help.
    • Knees brought together may change the presentation of early decelerations if the baby is coming through the pelvis.
  • Oxygen administration: Apply 10 liters of oxygen via non-rebreather facemask.
  • Discontinue Pitocin (oxytocin).

Resources to Practice

• The National Certification Corporation has a free online game to practice strip interpretation.