Fetal Heart Rate Monitoring:
Terminology Update
Sharon Fickley, BSN, RNC-OB
Laura Hall, ADN, RNC-OB
January 24th, 2011
Objectives
1.
2.
3.
Provide brief review of National Institute of Child
Health and Human Development (NICHD) 2008
Electronic Fetal Monitoring (EFM) Terminology
Update
Discuss physiologic basis for interpreting Fetal
Heart Rate (FHR) tracings
Introduce definitions of NICHD Categories for
interpreting and discussing FHR tracings
Background
 2008

Workshop
Key Players:
• National Institute of Child Health and Human
Development
• American College of Obstetricians and Gynecologists
(ACOG)
• Society for Maternal-Fetal Medicine
Background (con’t)
 Purposes:


Review & Update FHR pattern definitions
Assess existing classification systems for
interpreting FHR patterns
• Make recommendations about system for use in U.S.
• Make recommendations for research priorities regarding
EFM
(ACOG, 2009)
Purpose
“Using a common language for discussion of
fetal status is a key principle of effective
clinical communication and has the potential to
decrease communication errors”
(AWHONN, 2009, p. 72)
Methods

Systematic Assessment is Key
 Systematic Assessment of FHR tracing includes:
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Baseline Rate
Variability
Periodic or Episodic Changes
Uterine Activity
Pattern of or changes in FHR over time
Evaluation of findings within total clinical picture
(AWHONN, 2009)
Baseline Rate
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Approximate mean FHR rounded to increments of 5 bpm
during a 10 minute window, excluding accelerations and
decelerations and periods of marked variability
Must have at least 2 minutes identifiable, but not necessarily
contiguous, baseline segments
If don’t have at least 2 minutes of baseline in 10 minute
period, baseline is indeterminate
May need to refer to previous 10 minute window to determine
baseline
(Macones et al, 2008)
Baseline
Bradycardia: < 110 bpm
Tachycardia: >160 bpm
(Macones, et al, 2008)
Baseline Variability

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Determined in 10 minute window
Excluding accelerations or decelerations
Defined as fluctuations in baseline FHR that are irregular in
amplitude {height} and frequency {width} and are visually
quantified as the amplitude of the peak-to-trough in beats per
minute (bpm)

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Absent: amplitude range undetectable
Minimal: amplitude range visually detectable but </= 5 bpm (greater
than undetectable but </= 5 bpm)
Moderate: amplitude range 6-25 bpm
Marked: amplitude range > 25 bpm
(Macones, et al, 2008)
Periodic/Episodic Changes Accelerations
Acceleration: Visually apparent abrupt increase in FHR

Onset to peak <30 seconds

>/= 32 weeks: Peak >/= 15 bpm, lasting >/= 15 seconds
from beginning to return to baseline


<32 weeks: Peak >/= 10 bpm, lasting >/= 10 seconds –
>/= 10 minute acceleration = baseline change
(Macones, et al, 2008)
Periodic/Episodic Changes Decelerations
Early Deceleration:
 usually symmetrical
 gradual decrease and return of FHR
 associated with contraction
 onset to nadir >/= 30 seconds
 nadir coincides with peak of contraction
(Macones, et al, 2008)
Periodic/Episodic Changes Decelerations
Late Deceleration:
 usually symmetrical
 gradual decrease and return to baseline
 associated with contraction
 delayed in timing
 nadir occurs after peak of contraction
 generally, onset, nadir, and recovery occur after
the beginning, peak, and end of the contraction
(Macones, et al, 2008)
Periodic/Episodic Changes Decelerations
Variable Deceleration:

Abrupt decrease
 Onset to nadir <30 seconds
 Decrease is >/= 15 bpm, lasting >/= 15 seconds and <
2 minutes
 If associated with contractions, onset, depth and
duration commonly vary with successive contractions
(Macones, et al, 2008)
Periodic/Episodic Changes Decelerations
Prolonged Deceleration:

Decrease from baseline >/= 15 bpm
 Lasts >/= 2 minutes but < 10 minutes
 Deceleration lasting > 10 minutes = baseline change
Recurrent: occurring with >/= 50% contractions in any 20
minute window
Intermittent: occurring with < 50% contractions in any 20
minute window
(Macones, et al, 2008)
Uterine Activity
Normal Uterine Activity: Five or fewer uterine
contractions in 10 minutes, averaged over a 30 minute window
Tachysystole:
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More than five contractions in 10 minutes, averaged over a 30
minute period
Should always be discussed in conjunction with FHR
characteristics
Terms “Hyperstimulation” & “Hypercontractility” not defined,
should not be used
(ACOG, 2009; AWHONN 2009)
Terminology
Reactive and Nonreactive: apply to antepartum
monitoring (non-stress test) vs. intrapartum
Reassuring and Nonreassuring: Not used or addressed
in new terminology. AWHONN FHM course states
that one can feel reassured by a tracing, based upon
the Category it is in.
(AWHONN, 2009 & 2010)
Three Tiered System
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Represents analysis of fetal acid-base status at the time
assessment is made
Category I: Normal acid-base status likely – probability
high that fetus is well oxygenated
Category II: Indeterminate. Fetus likely exhibiting
compensatory response – has “reserves”
Category III: Abnormal fetal acid-base status likely
All definitions related to categories and their description are
adapted from Macones, et al, 2008.
Points to Emphasize
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FHR patterns change over time
Clinical management individualized for each situation
Must evaluate entire clinical picture, including risk factors for
both mother and baby
All interpretation and management based upon understanding
of physiologic mechanisms underlying FHR tracing
Fetal monitoring is a collaborative process of continual
assessment, interpretation, diagnosis, intervention, and
evaluation
Three Tiered System for Classifying
FHR Tracings
Category I
All of the Following:

Baseline 110-160
 Variability: Moderate
 Late or Variable
Decels: Absent
 Early Decelerations:
Present or Absent
 Accelerations:
Present or Absent
Category II
Examples:
 Moderate Variability
with recurrent late or
variable decelerations
 Minimal Variability with
recurrent variable
decelerations
 Absent Variability
WITHOUT recurrent
decelerations
 Bradycardia with
Moderate Variability
 Prolonged Decelerations
Category III
Either:
 Absent Variability with:
 Recurrent late decels
OR
 Recurrent variable
decels OR
 Bradycardia
OR:

Sinusoidal Pattern
Category I Overview
 Category
I tracings are normal
 Strongly predictive of normal fetal acid-base
status
 May be followed in routine manner
Category II Overview
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Includes all tracings not categorized as Category I or III
Not predictive of either normal or abnormal fetal acid-base status
No evidence to categorize as either I or III
Generally require “evaluation, and continued surveillance and reevaluation,
taking into account the entire associated clinical situation” (Macones 2008)
Additional tests (i.e. biophysical profile, amniotic fluid volume) may be
needed to gather all information required to plan management
May require intrauterine resuscitative measures
MOST IMPORTANT: try to identify &/or address underlying
physiologic mechanism which may be resulting in the characteristics of the
tracing
Category II Overview

Communicate with care provider
 Continue to evaluate and respond to tracing
 Implement intrauterine resuscitative measures as
needed to attempt correction of underlying
mechanism of FHR pattern characteristics
 Consider tocolytics if intrauterine resuscitative
measures do not bring resolution
Category III Overview

Are abnormal
 Associated with abnormal fetal acid-base balance at time of
observation
 Must evaluate and intervene quickly
 Make efforts to resolve quickly:
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Change maternal position
Discontinue labor stimulation
Administer IV fluids
Treat maternal hypotension
Provide oxygen to mother
Request tocolytics if appropriate
Mobilize team response
Category III Overview
 If
Category III tracing does not resolve
relatively quickly with physiologically-based
interventions, plan for expedited delivery
 Medical provider should be notified
immediately when tracing is a Category III
What does it mean for us?
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“Data concerning the FHR pattern should ideally be conveyed
using the definitions provided in the proceedings of the
NICHD 2008 guidelines for EFM definitions, interpretation,
and research” (AWHONN, 2009, p.178; Macones, et al, 2008)
Terminology should be defined in each institution’s policies
(AWHONN, 2009)
“AWHONN and ACOG support use of 2008 NICHD
guidelines for EFM definitions, interpretation, and research”
(AHWONN, 2009, p. 182)
Questions
References
American College of Obstetricians and Gynecologists. (2009b). Intrapartum
fetal heart rate monitoring: Nomenclature, interpretation, and general
management principles (Practice Bulletin 106). Washington, DC: Author.
Association of Women’s Health, Obstetrical and Neonatal Nursing. (2010).
Intermediate Fetal Monitoring Course. (5th Edition). Washington, DC:
Author.
Association of Women’s Health, Obstetrical and Neonatal Nursing. (2009).
Fetal Heart Monitoring Principles and Practice. (4th Edition). Washington,
DC: Author.
References (con’t)
Macones, G.A., Hankins, G. D., Spong, C.Y., Hauth, J.D., & Moore, T.
(2008). The 2008 National Institute of Child Health and Development
workshop report on electronic fetal monitoring: Update on definitions,
interpretations, and research guidelines. Obstetrics and Gynecology, 112,
661-666; and Journal of Obstetric, Gynecologic and Neonatal Nursing, 37,
510-515.