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The first central concept of standardized intrapartum FHR interpretation is that all clinically significant FHR decelerations (variable, late, or prolonged) reflect interruption of the pathway of oxygen transfer from the environment to the fetus at 1 or more points .
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The second central concept of standardized intrapartum FHR interpretation is that intrapartum interruption of fetal oxygenation does not result in CP unless the fetal response progresses to the stage of significant fetal metabolic acidemia (umbilical artery pH <7.0 and base deficit ≥12 mmol/L).
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The third central concept of intrapartum FHR interpretation is that moderate (normal) variability and / or accelerations reliably predict the absence of fetal metabolic acidemia at the time they are observed.
Category I: NORMALFHR tracings include ALL of the following:
Baseline rate: 110–160 beats per minute (bpm)Baseline FHR variability: moderateLate or variable decelerations: absentEarly decelerations: present or absentAccelerations: present or absent
Strongly predictive of normal acid-base status at time of observation.
Routine care; no specific action required
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Category III: ABNORMALFHR tracings include EITHER of the ff:
Absent baseline FHR variability and any of the ff: Recurrent late decelerations Recurrent variable decelerations Bradycardia
Sinusoidal pattern
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Category II: INDETERMINATEincludes all FHR tracings NOT categorized
as Category I or III. NOT predictive of either normal or
abnormal fetal acid-base status. requires continued surveillance and re-
evaluation- second recommendation is incomplete
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Classifications of VariabilityAbsent: amplitude range undetectable.
Minimal: amplitude range ≤5 bpm.
Moderate: amplitude range 6-25 bpm.
Marked: amplitude range >25 bpm.
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110 BPM
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160 BPM
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From the onset of the deceleration to the beginning of the FHR nadir of <30 seconds.
The decrease in FHR is ≥15 beats per minute, lasting ≥15 seconds, and <2 minutes in duration
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Variable DecelerationsSevere
≥ 60 seconds in duration & < 70 beats/min OR≥ 2 mins in duration & < 80 beats/min
Moderate30-60 sec in duration & < 70 beats/min OR≥ 60 sec in duration & < 80 beats/min
MildAll other decelerations are mild
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Variable Decelerations - Notice that the decelerations are not related to the contraction, beginning well before the contraction even begins.mcu pgc '10
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from the onset to the nadir of the deceleration of ≥30 seconds.
The nadir of the deceleration occurring after the peak of the contraction.
In most cases, the onset, nadir, and recovery of the deceleration occur after the beginning, peak, and ending of the contraction, respectively.
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Late Deceleration with Absent Variability – Notice the decrease in the fetal heart rate only begins to decline after the contraction peaks. mcu pgc '10
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from the onset to the FHR nadir of ≥30 seconds.
The nadir of the deceleration occurs at the same time as the peak of the contraction.
n most cases the onset, nadir, and recovery of the deceleration are coincident with the beginning, peak, and ending of the contraction, respectively.
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