CTG

Question 1

what is CTG and what is it used for?

Answer 1

CTG= cardiotocography

Looks at fetal heart rate over time

used as a measure of fetal wellbeing both in the antenatal period and during labour

Question 2

what are the 4 parameters of a CTG?

Answer 2

1. baseline HR 2. variability 3. accelerations 4. decelerations

Question 3

you look at a CTG and it appears like a sawtoothed/sinusoidal pattern.

what do you think of?

Answer 3

fetal anemia

Question 4

why do we see variability on a CTG?

Answer 4

due to the waxing and waning nature of sympathetic and parasympathetic nervous stimulation in the fetus

Question 5

what forms of variability indicate hypoxia on a CTG?

Answer 5

increased variability- >25bpm and less than 3bpm

Question 6

what are some causes of reduced variability on a CTG?

Answer 6

think SSSS!

Sleep

Sick (hypoxia)

Submature (prematurity)

Sedation (drugs)

Question 7

normal values for variability on a CTG?

Answer 7

5-25 bpm from baseline

Question 8

what do we mean by a ‘reactive CTG’?

Answer 8

normal variability is demonstrated

Question 9

what must we do if there are signs of fetal respiratory distress + hypoxia during labour?

Answer 9

emergency C-section

Question 10

what are the 4 types of decelerations on a CTG?

Answer 10

early and late decelerations

variable and prolonged decelerations

Question 11

what do late decelerations indicate on a CTG?

what exactly is a late deceleration?

what must we do?

Answer 11

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

Question 12

what is a cause of variable decelerations on CTG?

Answer 12

umbilical cord compression

Question 13

what are some features of CTG which may indicate SEVERE VARIABLE DECELERATION indicating fetal hypoxia?

Answer 13

Deep and wide- >60bpm and >60secs or Delayed recovery or rebound tachycardia

Question 14

what are the possible causes of prolonged deceleration on CTG?

Answer 14

sustained hypoxia causing sustained bradycardia can be due to:

cord compression

maternal hypotension

sustained uterine contraction

placental abruption

Question 15

In the antenatal period you notice that the CTG is non-reactive. what do you want to do to ix further?

Answer 15

doppler ultrasound looking for uterine artery waveforms!

Question 16

what might you do if you notice the CTG has absent variability, sinusoidal pattern and late deceleration?

Answer 16

emergency C section if baby is > 24 weeks gestation and viable

Question 17

in the intrapartum period you notice that the CTG is grossly abnormal and indicating foetal hypoxia. what should you do?

Answer 17

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

Question 18

what are the two components of a CTG?

Answer 18

the top part indicates the baseline fetal HR and variability

the bottom part of the CTG ‘toco’ is the contractions of the uterus

Question 19

what are the normal values for baseline HR on a CTG?

Answer 19

110-160bpm

Question 20

how do we determine the baseline HR on a CTG?

Answer 20

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.

Question 21

what might you think if you cannot see uterine contractions on a CTG?

Answer 21

antenatal CTG

Question 22

What exactly do we mean by variability on a CTG? what are we looking for on the CTG?

Answer 22

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

Question 23

what must we do first if we get an indeterminate CTG instead of immediately sending the woman to theatre for a c-section?

Answer 23

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.

Question 24

what is the normal acceleration rate on a CTG?

Answer 24

2 accelerations in 15 secs

Question 25

decelerations during an antenatal trace is….?

Answer 25

abnormal!

Question 26

what is the time period per square on a CTG?

Answer 26

small square= 30s

large square= 1min

Question 27

if you see reduced variability on a CTG is it an emergency?

Answer 27

need to evaluate over 40mins.

If > 40mins reduced variability then CTG abnormal.

Consider your 4 SSSS

Sleeping

Sedated

Submature

Sick

Question 28

on a ctg, what exactly do we mean by an acceleration? what are we looking at?

Answer 28

if the baseline fetal HR rapidly trends up then it is an acceleration generally

Question 29

describe what we mean by an ‘early deceleration’?

Answer 29

deceleration that occurs DURING uterine contractions.

Increased vagal tone due to increased fetal ICP

this is physiological and resolves after the contraction ends.

Question 30

what do we mean by a ‘variable deceleration’ and what must we do?

Answer 30

Variable decelerations are observed as a rapid fall in baseline rate with a variable recovery phase.

They are variable in their duration and may not have any relationship to uterine contractions.

Can indicate cord compression

We need to closely monitor the CTG.

Change the maternal position to see if it relieves the variable decelerations

Question 31

what exactly do we mean by prolonged decelerations?

Answer 31

A deceleration that last more than 2 minutes.

If it lasts between 2-3 minutes it is classed as non-reassuring.

If it lasts longer than 3 minutes it is immediately classed as abnormal.

Question 32

what are the antenatal indications for CTG during labour?

Answer 32

Abnormal antenatal CTG

• Abnormal Doppler umbilical artery velocimetry
• Suspected or confirmed intrauterine growth restriction
• Oligohydramnios or polyhydramnios
• Prolonged pregnancy >42 weeks gestation
• Multiple pregnancy
• Breech presentation
• Antepartum haemorrhage
• Prolonged rupture of membranes (>24 hours)
• Known fetal abnormality which requires monitoring
• Prior uterine scar / caesarean section
• Essential hypertension or pre-eclampsia
• Diabetes where medication is indicated or poorly controlled, or with fetal macrosomia
• Other current or previous obstetric or medical conditions which constitute a significant risk of fetal compromise e.g. cholestasis, isoimmunisation, substance abuse
• Decreased fetal movements
• Maternal age greater than or equal to 42

Question 33

what are the intrapartum indications for CTG monitoring during labour?

Answer 33

Induction of labour with prostaglandin / oxytocin

Abnormal auscultation or CTG

• Oxytocin augmentation
• Regional analgesia e.g. epidural or spinal, paracervical block
• Abnormal vaginal bleeding in labour
• Maternal pyrexia greater than or equal to 38°C
• Meconium or blood stained liquor
• Absent liquor following amniotomy
• Active first stage of labour >12 hours (i.e. after diagnosis of labour)
• Active second stage (i.e. pushing) >1 hour where birth is not imminent
• Preterm labour less than 37 completed weeks
• Tachysystole (more than 5 active labour contractions in 10 minutes, without fetal heart rate changes)
• Uterine hypertonus (contractions lasting more than 2 minutes or occurring within 60s of each other, without fetal heart rate changes
• Uterine hyperstimulation (tachysystole/hypertonus with fetal heart rate changes).