NICHD Terminology (National Certification Corporation, 2010, pg 2)
-Definitions are to be used for visual interpretation
-Definitions would apply to patterns obtained from internal or external monitoring
-The focus would be on intrapartum patterns, but the definitions would also appy to antepartum observation
-Fetal heart rate patterns are defined as baseline, periodic or episodic. Periodic patterns are those that are associated withcontractions. Episodic patterns are NOT associated with contractions.
-Fetal heart rate patterns and uterine activity would be determined through interpretation of tracings of good quality
-The components of fetal heart rate tracings do not occur in isolation, therefore evaluation of fetal heart rate patterns should take into account all components of fetal heart rate pattern, including baseline, variability, and presence of accelerations or decelerations.
- Fetal heart rate tracings should be assessed over time to identify changes and trends
- Accelerations and decelerations are determined based on the adjacent baseline fetal heart rate
- Periodic patterns are identified based on the type waveform defined as abrupt vs. gradual onset of the deceleration
- No differentiation between short and long term variability was made because in practice, they are visually determined as a unit.
-EFM patterns are dependend on gestational age so this is an important factor for evaluation. Maternal medical status, prior fetal assessment results, use of medications and other factors also may need to be considered
- A complete description of the EFM tracing includes uterine contractions, baseline fetal heart rate, baseline variability, presence of accelerations, periodic or episodic decelerations, and trends of the fetal heart rate pattern over time.
-Definitions are to be used for visual interpretation
-Definitions would apply to patterns obtained from internal or external monitoring
-The focus would be on intrapartum patterns, but the definitions would also appy to antepartum observation
-Fetal heart rate patterns are defined as baseline, periodic or episodic. Periodic patterns are those that are associated withcontractions. Episodic patterns are NOT associated with contractions.
-Fetal heart rate patterns and uterine activity would be determined through interpretation of tracings of good quality
-The components of fetal heart rate tracings do not occur in isolation, therefore evaluation of fetal heart rate patterns should take into account all components of fetal heart rate pattern, including baseline, variability, and presence of accelerations or decelerations.
- Fetal heart rate tracings should be assessed over time to identify changes and trends
- Accelerations and decelerations are determined based on the adjacent baseline fetal heart rate
- Periodic patterns are identified based on the type waveform defined as abrupt vs. gradual onset of the deceleration
- No differentiation between short and long term variability was made because in practice, they are visually determined as a unit.
-EFM patterns are dependend on gestational age so this is an important factor for evaluation. Maternal medical status, prior fetal assessment results, use of medications and other factors also may need to be considered
- A complete description of the EFM tracing includes uterine contractions, baseline fetal heart rate, baseline variability, presence of accelerations, periodic or episodic decelerations, and trends of the fetal heart rate pattern over time.
FETAL HEART RATE BASELINE
The mean fetal heart rate is rounded to increments of 5 beats per minute during a 10 minute segment excluding accelerations and decelerations, periods of marked variability, or baseline segments that differ by more than 25 beats per minute.
In any given 10 minute window, the minimum baseline duration must be at least 2 minutes (not necessarily contiguous). Otherwise, it is considered indeterminate. In these instances, review of the previous 10 minute segments should be the basis on which to determine the baseline.
In determining the baseline rate, a minimum of a 10 minute period of monitoring is necessary for confirmation of the rate.
The fetal baseline rate is classifi ed as follows:
Normal: 110 to 160 beats per minute
Bradycardia: Less than 110 beats per minute
Tachycardia: Over 160 beats per minute
The mean fetal heart rate is rounded to increments of 5 beats per minute during a 10 minute segment excluding accelerations and decelerations, periods of marked variability, or baseline segments that differ by more than 25 beats per minute.
In any given 10 minute window, the minimum baseline duration must be at least 2 minutes (not necessarily contiguous). Otherwise, it is considered indeterminate. In these instances, review of the previous 10 minute segments should be the basis on which to determine the baseline.
In determining the baseline rate, a minimum of a 10 minute period of monitoring is necessary for confirmation of the rate.
The fetal baseline rate is classifi ed as follows:
Normal: 110 to 160 beats per minute
Bradycardia: Less than 110 beats per minute
Tachycardia: Over 160 beats per minute
FETAL HEART RATE PATTERNS
Determination of baseline fetal heart rate variability is based on visual assessment and excludes sinusoidal
patterns.
Variability is defined as fluctuations in the fetal heart rate baseline that are irregular in amplitude and frequency. The visual quantification of the amplitude from peak to trough in beats per minute is as follows:
Variability Amplitude Range Classification
Undetectable- Absent
Undetectable to equal to or less than 5 beats per minute- Minimal
6 to 25 beats per minute- Moderate
More than 25 beats per minutes- Marked
A sinusoidal fetal heart rate pattern is a specific fetal heart rate pattern and described as a smooth, sine
wave-like undulating pattern with a cycle frequency of 3 to 5 beats per minute that continues for at least
20 minutes or more.
ACCELERATIONS
Based on visual assessment, an acceleration is defined as an abrupt increase of at least 15 beats per minute in fetal heart rate above the baseline. Onset to peak is less than 30 seconds and duration is equal to or more than 15 seconds and less than two minutes from onset to return to baseline.
In pregnancies less than 32 weeks gestation, accelerations are defined as an increase of 10 beats per minute or more above baseline which lasts 10 seconds or more.
An acceleration is classifi ed as prolonged if the duration is 2 minutes or more but less than 10 minutes.
Accelerations that are 10 minutes or more are considered a baseline change.
LATE DECELERATIONS
Based on visual assessment, a late deceleration is defined as a usually symmetrical, gradual decreasein fetal heart rate and return to baseline associated with uterine contractions. Onset to nadir is equal to or greater than 30 seconds. The nadir of the deceleration usually occurs after the peak of the contraction.
EARLY DECELERATIONS
Based on visual assessment, an early deceleration is defined as a usually symmetrical, gradual decrease in fetal heart rate and return to baseline associated with uterine contractions. Onset to nadir is equal to or greater than 30 seconds. The nadir of the deceleration usually occurs at the same time of the peak of the contraction.
VARIABLE DECELERATIONS
Based on visual assessment, a variable deceleration is defined as an abrupt decrease in fetal heart rate below the baseline which may or may not be associated with uterine contractions. Onset to beginning of nadir is less than 30 seconds. The decrease in fetal heart rate below the baseline is equal to or more than 15 beats per minute, lasting 15 seconds or more, but less than 2 minutes in duration from onset to return to baseline.
When variable decelerations occur in conjunction with uterine contractions, the onset, depth and duration vary with each succeeding uterine contraction.
PROLONGED DECELERATION
Based on visual assessment, a prolonged deceleration is defined as a decrease in fetal heart rate below the baseline. The decrease in the fetal heart rate is 15 beats per minute or more and lasts for at least 2 minutes but less than 10 minutes from onset to return to baseline. A prolonged deceleration that is sustained for 10 minutes or more is a baseline change.
Determination of baseline fetal heart rate variability is based on visual assessment and excludes sinusoidal
patterns.
Variability is defined as fluctuations in the fetal heart rate baseline that are irregular in amplitude and frequency. The visual quantification of the amplitude from peak to trough in beats per minute is as follows:
Variability Amplitude Range Classification
Undetectable- Absent
Undetectable to equal to or less than 5 beats per minute- Minimal
6 to 25 beats per minute- Moderate
More than 25 beats per minutes- Marked
A sinusoidal fetal heart rate pattern is a specific fetal heart rate pattern and described as a smooth, sine
wave-like undulating pattern with a cycle frequency of 3 to 5 beats per minute that continues for at least
20 minutes or more.
ACCELERATIONS
Based on visual assessment, an acceleration is defined as an abrupt increase of at least 15 beats per minute in fetal heart rate above the baseline. Onset to peak is less than 30 seconds and duration is equal to or more than 15 seconds and less than two minutes from onset to return to baseline.
In pregnancies less than 32 weeks gestation, accelerations are defined as an increase of 10 beats per minute or more above baseline which lasts 10 seconds or more.
An acceleration is classifi ed as prolonged if the duration is 2 minutes or more but less than 10 minutes.
Accelerations that are 10 minutes or more are considered a baseline change.
LATE DECELERATIONS
Based on visual assessment, a late deceleration is defined as a usually symmetrical, gradual decreasein fetal heart rate and return to baseline associated with uterine contractions. Onset to nadir is equal to or greater than 30 seconds. The nadir of the deceleration usually occurs after the peak of the contraction.
EARLY DECELERATIONS
Based on visual assessment, an early deceleration is defined as a usually symmetrical, gradual decrease in fetal heart rate and return to baseline associated with uterine contractions. Onset to nadir is equal to or greater than 30 seconds. The nadir of the deceleration usually occurs at the same time of the peak of the contraction.
VARIABLE DECELERATIONS
Based on visual assessment, a variable deceleration is defined as an abrupt decrease in fetal heart rate below the baseline which may or may not be associated with uterine contractions. Onset to beginning of nadir is less than 30 seconds. The decrease in fetal heart rate below the baseline is equal to or more than 15 beats per minute, lasting 15 seconds or more, but less than 2 minutes in duration from onset to return to baseline.
When variable decelerations occur in conjunction with uterine contractions, the onset, depth and duration vary with each succeeding uterine contraction.
PROLONGED DECELERATION
Based on visual assessment, a prolonged deceleration is defined as a decrease in fetal heart rate below the baseline. The decrease in the fetal heart rate is 15 beats per minute or more and lasts for at least 2 minutes but less than 10 minutes from onset to return to baseline. A prolonged deceleration that is sustained for 10 minutes or more is a baseline change.
Electronic Fetal Monitoring
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