CTG Flashcards
what is CTG and what is it used for?
CTG= cardiotocography
Looks at fetal heart rate over time
used as a measure of fetal wellbeing both in the antenatal period and during labour
what are the 4 parameters of a CTG?
- baseline HR 2. variability 3. accelerations 4. decelerations
you look at a CTG and it appears like a sawtoothed/sinusoidal pattern.
what do you think of?
fetal anemia
why do we see variability on a CTG?
due to the waxing and waning nature of sympathetic and parasympathetic nervous stimulation in the fetus
what forms of variability indicate hypoxia on a CTG?
increased variability- >25bpm and less than 3bpm
what are some causes of reduced variability on a CTG?
think SSSS!
Sleep
Sick (hypoxia)
Submature (prematurity)
Sedation (drugs)
normal values for variability on a CTG?
5-25 bpm from baseline
what do we mean by a ‘reactive CTG’?
normal variability is demonstrated
what must we do if there are signs of fetal respiratory distress + hypoxia during labour?
emergency C-section
what are the 4 types of decelerations on a CTG?
early and late decelerations
variable and prolonged decelerations
what do late decelerations indicate on a CTG?
what exactly is a late deceleration?
what must we do?
Late decelerations begin at the peak of uterine contraction and recover after the contraction ends.
This type of deceleration indicates there is insufficient blood flow through the uterus and placenta.
As a result blood flow to the foetus is significantly reduced causing foetal hypoxia and acidosis.
If we see this we must take a fetal scalp lactate. If abnormal i.e. > 4.8, then emergency c-section is required
what is a cause of variable decelerations on CTG?
umbilical cord compression
what are some features of CTG which may indicate SEVERE VARIABLE DECELERATION indicating fetal hypoxia?
Deep and wide- >60bpm and >60secs or Delayed recovery or rebound tachycardia
what are the possible causes of prolonged deceleration on CTG?
sustained hypoxia causing sustained bradycardia can be due to:
cord compression
maternal hypotension
sustained uterine contraction
placental abruption
In the antenatal period you notice that the CTG is non-reactive. what do you want to do to ix further?
doppler ultrasound looking for uterine artery waveforms!
what might you do if you notice the CTG has absent variability, sinusoidal pattern and late deceleration?
emergency C section if baby is > 24 weeks gestation and viable
in the intrapartum period you notice that the CTG is grossly abnormal and indicating foetal hypoxia. what should you do?
Deliver the baby!
If the cervix is fully dilated and the head is low and engaged in vaginal canal–> suction/vacuum or forceps
if NOT, then emergency C-SECTION
what are the two components of a CTG?
the top part indicates the baseline fetal HR and variability
the bottom part of the CTG ‘toco’ is the contractions of the uterus
what are the normal values for baseline HR on a CTG?
110-160bpm
how do we determine the baseline HR on a CTG?
look at the trace between uterine contractions to determine baseline HR
The baseline rate is the average heart rate of the foetus within a 10 minute window.
what might you think if you cannot see uterine contractions on a CTG?
antenatal CTG
What exactly do we mean by variability on a CTG? what are we looking for on the CTG?
determine the baseline fetal HR and look at the peaks and troughs of the trace. Usually peaks and troughs 5-25bpm around baseline. If less then 5bpm then we say it is absent or reduced variability
what must we do first if we get an indeterminate CTG instead of immediately sending the woman to theatre for a c-section?
Check whether the fetal HR recorded on the CTG or u/s is actually the fetus and not the maternal HR.
Do this by timing the maternal pulse or putting on a sat probe, and or placing a fetal scalp clip to more accurately check the fetal HR.
If still indeterminate and the baby is cephalic presentation, do a fetal scalp lactate. if > 4.8, send to theatre.
what is the normal acceleration rate on a CTG?
2 accelerations in 15 secs
