How do you interpret an Electronic Fetal Monitoring (EFM) strip?

How to Read an Electronic Fetal Monitoring (EFM) Strip

Use the systematic DR C BRAVADO mnemonic to interpret EFM strips, which provides a structured approach to assess all critical components and classify tracings into the NICHD three-category system for appropriate clinical action. 1

Systematic Interpretation Framework: DR C BRAVADO

DR: Determine Risk

• Identify whether the clinical situation represents high, medium, or low risk for fetal compromise 1
• High-risk conditions (growth restriction, preeclampsia, infection) warrant more aggressive interpretation and lower threshold for intervention 2

C: Contractions

• Assess rate, rhythm, frequency, duration, intensity, and resting tone of uterine contractions 1
• Normal contraction pattern is no more than 5 contractions in a 10-minute period (averaged over 30 minutes) 1
• Tachysystole (more than 5 contractions per 10 minutes) should be qualified by presence or absence of decelerations 1

BRA: Baseline Rate

• Normal baseline: 110-160 bpm 1
• Bradycardia: < 110 bpm 1
• Tachycardia: > 160 bpm 1
• Baseline must be sustained for at least 10 minutes to be classified 3

V: Variability (Most Critical Component)

• Moderate variability (6-25 bpm) is reassuring and predicts absence of fetal acidemia 2
• Minimal variability: < 6 bpm 1
• Absent variability: no visible fluctuation 1
• Marked variability: > 25 bpm 1
• Absent variability combined with decelerations or bradycardia defines true non-reassuring patterns 2

Common Pitfall: Fetal sleep cycles (20-40 minutes) and medications (analgesics, anesthetics, magnesium sulfate) can temporarily decrease variability without indicating fetal compromise 1, 2

A: Accelerations

• Abrupt increases in FHR ≥ 15 bpm lasting ≥ 15 seconds indicate fetal well-being 1
• For preterm fetuses: ≥ 10 bpm lasting ≥ 10 seconds 1
• Accelerations are associated with fetal movement or stimulation 1

D: Decelerations

• Early decelerations: Gradual onset coincident with contractions; benign 1
• Variable decelerations: Abrupt onset, variable timing; suggest cord compression 1
• Late decelerations: Gradual onset after contraction begins, nadir after contraction peak; suggest uteroplacental insufficiency 1
• Prolonged decelerations: Lasting 2-10 minutes with abrupt onset 1

O: Overall Assessment Using NICHD Categories

NICHD Three-Category Classification System

Category I (Normal) - Continue Current Monitoring

• Normal baseline FHR (110-160 bpm) 1
• Moderate baseline variability 1
• Late or variable decelerations absent 1
• Accelerations present or absent 1
• Management: Continue current monitoring method 1

Category II (Indeterminate) - Implement General Measures

This category includes all tracings not classified as Category I or III and represents the majority of clinical tracings 1

Examples include:

• Tachycardia or bradycardia without absent variability 1
• Minimal, absent (without decelerations), or marked variability 1
• Variable or late decelerations with preserved variability 1
• No accelerations after fetal stimulation 1

Management approach:

• Implement general measures: vaginal examination, check maternal vital signs, administer oxygen (6-10 L/min), change maternal position to left lateral, give IV fluid bolus, assess fetal pH with acoustic or scalp stimulation 1, 2
• Consider discontinuing oxytocin 1
• Consider expedited delivery if abnormalities persist or worsen 1, 2

Category III (Abnormal) - Expedite Delivery

Absent baseline FHR variability with any of the following:

• Recurrent late decelerations 1
• Recurrent variable decelerations 1
• Bradycardia 1
• Sinusoidal pattern 1

Management:

• Discontinue oxytocin immediately 1
• Expedite delivery by operative vaginal delivery or cesarean section 1
• Implement general resuscitative measures while preparing for delivery 2

Special Pattern: Sinusoidal Pattern

• Smooth, undulating sine wave pattern with amplitude of 10 bpm, 3-5 cycles per minute, lasting ≥ 20 minutes 1
• Associated with severe fetal anemia and hydrops; requires rapid intervention 1
• Benign-appearing similar patterns from fetal thumb sucking or maternal narcotics typically last < 10 minutes 1

Critical Clinical Pearls

The combination of absent variability with decelerations or bradycardia is what defines pathologic patterns requiring immediate action - isolated findings with preserved variability are generally not immediately concerning 2

Moderate variability is the single most reassuring finding on EFM and predicts absence of fetal acidemia regardless of other findings 2

Category II tracings require clinical context and serial assessment - they represent a spectrum from near-normal to near-abnormal 1