CTG defintions Flashcards
define baseline variability
The minor fluctuations around the baseline FHR. It is assessed by estimating the difference
in beats per minute between the highest peak and lowest trough of fluctuation in one minute segments of the trace between contractions.
Define normal baseline variability
6-25bpm
define reduced baseline variability
3-5bpm
define absent baseline variability
<3bpm
Define increased baseline variability
> 25bpm
define accelerations
Transient increases in FHR of 15 bpm or more above the baseline and lasting 15 seconds at the baseline. Accelerations in the preterm fetus may be of lesser amplitude and shorter duration. The significance of no accelerations on an otherwise normal CTG is unclear
Define Deceleration
Transient decreases of the FHR below the baseline lasting at least 15 seconds, conforming to one of the patterns below:
Define early decelerations
Uniform, repetitive decrease of FHR with slow onset early in the contraction and slow return to baseline by the end of the contraction
Define variable deceleration
Repetitive or intermittent decreasing of FHR with rapid onset and recovery. Time relationships with contraction cycle may be variable but most commonly occur simultaneously with contractions.
Define complicated variable decelerations
The following additional features increase the likelihood of fetal hypoxia: - Rising baseline rate or fetal tachycardia.
- Reducing baseline variability.
- Slow return to baseline FHR after the end of the contraction.
- Large amplitude (by 60 bpm or to 60 bpm) and/or long duration (60 seconds).
- Presence of smooth post deceleration overshoots (temporary smooth increase in FHR above baseline).
define prolonged decelerations
A fall in the baseline fetal heart rate for more than 90 seconds and up to 5 minutes
Define bradycardia
A fall in the baseline fetal heart rate for more than 5 minutes
