Cardiotocography (CTG) warda

I designed this presentation to be helpful for my junior colleagues .

1. CARDIOTOCOGRAPHY
By Osama M Warda , MD Professor of Obstetrics & Gynecology
Mansoura University- EGYPT

2. BACKGROUND
C
Cardiotocography (CTG) is a test used in pregnancy to
monitor both the fetal heart pattern as well as the
uterine contractions.
C
It should only used in the 3
rd
trimester when fetal neural
reflexes are present. C
Its purpose is to monitor fetal well-being & allows early
detection of fetal distress
antenatal
or
intra-partum
.
C
An abnormal CTG indicates the need for further invasive
investigation & ultimately may lead to emergency CS
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3. When to do CTG?
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4. Frequency of testing
-
Usually
every 7 days (i.e.
weekly
)
-
Twice-weekly
testing is advocated by some in :
A
Post term pregnancy
A
Diabetes mellitus
A
Fetal growth restriction,
A
Gestational hypertension
- Additional testing is performed for maternal or f etal deterioration
regardless of time elapsed
- Others perform non-stress tests daily or even more frequently

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5. The Machine
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6. O Warda 6

7. Application:
external; antenatal

C
The machine used is called cardio-tocograph.
C
It involves the placement of 2 transducers on the
abdomen of a pregnant woman: one transducer
records the fetal heart rate using ultrasound
beam , the other transducer records uterine
contractions by measuring the tension of the
maternal abdominal wall. This provides indirect
indication of the intrauterine pressure.
C
These recordings are blotted on a special paper.


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8. Application of the transducers
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Internal fetal monitoring
FSE

9. Application:
internal; intra-partum

C
The machine used is called cardio-tocograph.
C
It involves the placement of 2 transducers: a
fetal scalp electrode( FSE): an internal fetal heart
monitor , and intrauterine pressure
catheter(IUPC): an internal uterine contraction
monitor
C
These recordings are shown on a screen and
may be blotted on a special paper.

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10. Setting the CTG machine
Horizontal Scale Paper speed is set to 1,2,or 3 cm /minute. Vertical Scale: A
Sensitivity displays are set to 20 or 30 beats per
minute (bpm) /cm.
A
FHR range displays of 30–240 bpm .
A
Uterine Activity: Internal 0-100 mmHg
External 0-100 relat ive units
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11. Setting the CTG machine

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3cm / min
1cm / min
3 small vertical spaces / cm
10 beats / small space
F
H
R

Ut.
Cont.

12. Setting the CTG machine

C
Fetal heart rate is commonly recorded
with paper speed at 1 cm/ min compared
with 3 cm/min chart recorder.
C
3 cm: is the more accurate for abnormalities
C
1cm: less paper but less accurate : Used
for screening



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13. ACOUSTIC STIMULATION TESTS
C
Provoking acceleration of FHR.
C
The acoustic stimulator is positioned on the
maternal abdomen and a stimulus of 1 to 2 sec .
C
It may be repeated up to three times.
C
It shortened the average time for non-stress
testing from 24 to 15 minutes.

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14. Interpretation of CTG

C
To interpret a CTG you need a structured
method of assessing its various characteristics.
C
The most popular method can be remembered
using the acronym
DR C BRAVADO
-
DR=Define Risk . - C= Contractions
-
Bra= Baseline Rate - V=Variability
-
A= Accelerations - D= Decelerations
-
O= Overall impression
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15. D
efine
R
isk
R
You first need to assess if this pregnancy
is high or low risk
R
This is important as it gives more context
to the CTG reading ;
e.g. If the pregnancy is
high risk, your threshold for intervening
may be lowered.


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DR
C BRAVADO

16. D
efine
R
isk
High-risk pregnancies:
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DR
C BRAVADO

17. C
ontraction
3
Record the number of contractions present in a 10
minute period -
e.g. 3 in 10

3
Each big square is equal to 1 minute, so you look
how many contractions occurred in 10 squares 3
Individual contractions are seen as peaks on the part
of the CTG monitoring uterine activity 3
You should assess contractions for the following:
c
Duration –
how long do the contractions last?

c
Intensity –
how strong are the contractions? (assessed using pa lpation)


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DR
C
BRAVADO

18. O Warda 18
In this example there are 2-3 contractions in a 10 minute period
- e.g. 3 in 10

C
ontraction
DR
C
BRAVADO

19. B
aseline
R
ate of fetal heart
C
The baseline rate is the average heart rate of
the fetus in a 10 minute window.
C
Look at the CTG & assess what the average
heart rate has been over the last 10 minutes
C
Ignore any Accelerations or Decelerations
C
A normal fetal heart rate is between 120-160
bpm.

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DR C
BRA
VADO

20. B
aseline
R
ate of fetal heart
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DR C
BRA
VADO

21. B
aseline
R
ate of fetal heart
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DR C
BRA
VADO
If the causes of tachy-or-bradycardia cannot be identified and
corrected, immediate delivery is recommended

22. V
ariability
C
Baseline variability refers to the variation of fet al heart rate from
one beat to the next.
C
Variability occurs as a result of the interaction b etween the
nervous system, chemoreceptors, barorecptors & cardiac
responsiveness.
C
Therefore it is a good indicator of how healthy the fetus is at that
time.
C
This is because a healthy fetus will constantly be adapting it’s
heart rate to respond to changes in it’s environment.
C
Normal variability is between 10-25 bpm
C
To calculate variability you look at how much the peaks & troughs
of the heart rate deviate from the baseline rate
(in bpm)


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DR C BRA
V
ADO

23. V
ariability
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DR C BRA
V
ADO
Variability can be categorized as: •Reassuring
– ≥ 5 bpm
•
Non-reassuring
– < 5bpm for between 40-90 minutes
•
Abnormal
– < 5bpm for >90 minutes

24. V
ariability
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Reduced variability can be caused by: 1. Fetus sleeping -
this should last no longer than 40 minutes – most common cause
2.
Fetal acidosis (due to hypoxia) –
more likely if late decelerations also present
3.
Fetal tachycardia
4. Drugs –
opiates, benzodiazipine’s, methyldopa, magnesium sulphate
5.
Prematurity –
variability is reduced at earlier gestation (<28 we eks)
6.
Congenital heart abnormalities

DR C BRA
V
ADO

25. A
ccelerations
C
Accelerations are an abrupt increase in baseline heart rate of >15
bpm for >15 seconds. Its presence is
reassuring
C
Ante-natal there should be at least 2 accelerations every 15 minutes.
C
Accelerations occurring alongside uterine contractions is a sign of a
healthy fetus
C
However the absence of accelerations with
an otherwise normal CTG

is of uncertain significance

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DR C BRAV
A
DO

26. D
ecelerations

C
Decelerations are an abrupt decrease in baseline heart
rate of >15 bpm for >15 seconds C
There are a number of different types of decelerations,
each with varying significance 1. Early decelerations
2. Variable decelerations
3. Late decelerations
4. Prolonged decelerations
5. Sinusoidal pattern
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DR C BRAVA
D
O

27. D
ecelerations

1. Early deceleration C
Early decelerations start when uterine contraction begins & recover when
uterine contraction stops
C
This is due to increased fetal intracranial pressur e causing increased vagal
tone
C
It therefore quickly resolves once the uterine cont raction ends & intracranial
pressure reduces
C
This type of deceleration is therefore considered t o be
physiological
.

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DR C BRAVA
D
O

28. D
ecelerations

2. Variable Decelerations: C
Variable decelerations are seen as a rapid fall in b aseline rate with a variable
recovery phase.
C
They are variable in their duration & may not have any relationship to uterine
contractions
C
They are most often seen during labor & in patients with reduced amniotic fluid
volume
C
Variable decelerations are usually caused by
umbilical cord compression.
C
The umbilical
vein
is often occluded first causing an acceleration in response. Then the
umbilical
artery
is occluded causing a subsequent rapid deceleration.
C
When pressure on the cord is reduced another acceleration occurs & then the baseline
rate returns.
C
Accelerations before & after a variable deceleration are known as the
“shoulders of
deceleration”.
Their presence indicates the fetus is
not
yet hypoxic & is adapting to
the reduced blood flow.

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DR C BRAVA
D
O

29. D
ecelerations

2. Variable Decelerations: (continued) C
Variable decelerations can sometimes
resolve
if the mother changes
position
C
The presence of persistent variable decelerations indicates the need
for
close
monitoring
C
Variable decelerations
without
the shoulders is more
worrying
as it
suggests the fetus is hypoxic

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DR C BRAVA
D
O

30. D
ecelerations

3. Late deceleration C
Late decelerations begin at the
peak
of uterine contraction & recover
after
the
contraction ends.
C
This type of deceleration indicates there is
insufficient
blood flow through the uterus
& placenta. As a result blood flow to the fetus is significantly
reduced
causing fetal
hypoxia
&
acidosis

Reduced utero-placental blood flow can be caused by: C
Maternal hypotension
C
Pre-eclampsia
C
Uterine hyper-stimulation
NOTE:
The presence of late decelerations is
taken seriously & fetal blood sampling for pH is indicated, If fetal blood pH is acidotic it indicates significant foetal hypoxia & the need for emergency C-section
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DR C BRAVA
D
O

31. D
ecelerations

4.Prolonged deceleration C
A deceleration that last more than
2 minutes
C
If it lasts between
2-3 minutes
it is classed as
Non-Reasurring
C
If it lasts
longer than 3 minutes
it is immediately classed as
Abnormal
C
Action must be taken quickly – e.g. Fetal blood sampling / emergency
C-section

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DR C BRAVA
D
O

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33. D
ecelerations

5. Sinusoidal Pattern 3
This type of pattern is
rare
, however if present it is very serious
3
It is associated with high rates of fetal morbidity & mortality
3
It is described as:
c
A smooth, regular, wave-like pattern
c
Frequency of around 2-5 cycles a minute
c
Stable baseline rate around 120-160 bpm
c
No beat to beat variability

A sinusoidal pattern indicates:
m
Severe fetal hypoxia
m
Severe fetal anaemia
m
Fetal/Maternal Hemorrhage
Immediate C-section is indicated
for this kind of pattern. Outcome is usually poor
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DR C BRAVA
D
O

34. O
verall impression
- Once you have assessed all aspects of the CTG you need to give your
overall impression. The overall impression can be described as either:
3Reassuring
3Suspicious
3Pathological
-The overall impression is determined by how many of the CTG features were
either
reassuring
,
non-reassuring
or
abnormal
. The NICE guideline
demonstrates how to decide which category a CTG falls into:

1- Normal CTG=
All
four
features are classified as
reassuring
.
2-Suspicious CTG
=
One
feature is classified as
non-reassuring
while the
remaining features are reassuring
3- Pathological CTG
=
≥ 2
features
non-reassuring
, or
≥ 1
feature
classified as
abnormal

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DR C BRAVAD
O

35. O
verall impression


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DR C BRAVAD
O

36. INTRAPARTUM FETAL MONITORING
Monitoring uncomplicated pregnancy: - For a woman who is healthy and has had an otherwise
uncomplicated pregnancy, intermittent auscultation should be
offered and recommended in labor to monitor fetal well-being
using
Doppler
or
Pinard
.
-
In the active stages of labor, intermittent auscult ation should occur
after a contraction, for a minimum of 60 seconds, a nd at least:
- Every 15 minutes in the first stage
- Every 5 minutes in the second stage
-
The maternal pulse should be palpated if FHR abnormality
detected to differentiate the 2 heart rates.


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NICE 2007

37. INTRAPARTUM FETAL MONITORING
Continuous EFM In Low-risk Women:
Indications: 1.
Significant or light Meconium-stained liquor
2.
Abnormal FHR detected by intermittent auscultation
(< 110 bpm; or > 160 bpm, or any decelerations after a
contraction.
3.
Maternal pyrexia (defined as 38.0 °C once or 37.5 ° C on
two occasions 2 hours apart)
4.
Fresh bleeding developing in labor
5.
Oxytocin use for augmentation
6.
The woman’s request
.

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NICE 9- 2007

38. INTRAPARTUM FETAL MONITORING
Continuous EFM In Low-risk Women:
Evaluation
:
3
There was a borderline evidence that continuous EFM
were
more
likely to have an
instrumental
birth
compared with the auscultation group although
there
was
no
evidence of differences in:
c
Augmentation
c
Perinatal mortality
c
Other neonatal morbidities



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NICE 9- 2007

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