This document discusses cardiotocography (CTG), which monitors fetal heart rate and uterine contractions during pregnancy. CTG is performed in the third trimester using external transducers on the abdomen or internal monitors during labor. Recordings are interpreted using the DR C BRAVADO method: defining risk, assessing contractions, baseline rate, variability, accelerations, decelerations, and the overall impression. Abnormal findings like late decelerations or a sinusoidal pattern indicate fetal distress requiring emergency measures.

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

2. BACKGROUND
Cardiotocography (CTG) is a test used in pregnancy to
monitor both the fetal heart pattern as well as the
uterine contractions.
It should only used in the 3rd trimester when fetal neural
reflexes are present.
Its purpose is to monitor fetal well-being & allows early
detection of fetal distress antenatal or intra-partum.
An abnormal CTG indicates the need for further invasive
investigation & ultimately may lead to emergency CS
O Warda 2

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 :
Post term pregnancy
Diabetes mellitus
Fetal growth restriction,
Gestational hypertension
- Additional testing is performed for maternal or fetal 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
The machine used is called cardio-tocograph.
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.
These recordings are blotted on a special paper.
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8. Application of the transducers
O Warda 8Internal fetal monitoring
FSE

9. Application: internal; intra-partum
The machine used is called cardio-tocograph.
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
These recordings are shown on a screen and
may be blotted on a special paper.
O Warda 9

10. Setting the CTG machine
Horizontal Scale
Paper speed is set to 1,2,or 3 cm /minute.
Vertical Scale:
Sensitivity displays are set to 20 or 30 beats per
minute (bpm) /cm.
FHR range displays of 30–240 bpm .
Uterine Activity: Internal 0-100 mmHg
External 0-100 relative units
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11. Setting the CTG machine
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3cm / min1cm / min
3 small vertical spaces / cm
10 beats / small space
F
H
R
Ut.
Cont.

12. Setting the CTG machine
Fetal heart rate is commonly recorded
with paper speed at 1 cm/ min compared
with 3 cm/min chart recorder.
3 cm: is the more accurate for abnormalities
1cm: less paper but less accurate : Used
for screening
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13. ACOUSTIC STIMULATION TESTS
Provoking acceleration of FHR.
The acoustic stimulator is positioned on the
maternal abdomen and a stimulus of 1 to 2 sec .
It may be repeated up to three times.
It shortened the average time for non-stress
testing from 24 to 15 minutes.
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14. Interpretation of CTG
To interpret a CTG you need a structured
method of assessing its various characteristics.
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. Define Risk
You first need to assess if this pregnancy
is high or low risk
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. Define Risk
High-risk pregnancies:
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DR C BRAVADO

17. Contraction
Record the number of contractions present in a 10
minute period - e.g. 3 in 10
Each big square is equal to 1 minute, so you look
how many contractions occurred in 10 squares
Individual contractions are seen as peaks on the part
of the CTG monitoring uterine activity
You should assess contractions for the following:
Duration – how long do the contractions last?
Intensity – how strong are the contractions? (assessed using palpation)
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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
Contraction DR C BRAVADO

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

20. Baseline Rate of fetal heart
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DR C BRAVADO

21. Baseline Rate of fetal heart
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DR C BRAVADO
If the causes of tachy-or-bradycardia cannot be identified and
corrected, immediate delivery is recommended

22. Variability
Baseline variability refers to the variation of fetal heart rate from
one beat to the next.
Variability occurs as a result of the interaction between the
nervous system, chemoreceptors, barorecptors & cardiac
responsiveness.
Therefore it is a good indicator of how healthy the fetus is at that
time.
This is because a healthy fetus will constantly be adapting it’s
heart rate to respond to changes in it’s environment.
Normal variability is between 10-25 bpm
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 BRAVADO

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

24. Variability
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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 weeks)
6. Congenital heart abnormalities
DR C BRAVADO

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

26. Decelerations
Decelerations are an abrupt decrease in baseline heart
rate of >15 bpm for >15 seconds
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 BRAVADO

27. Decelerations
1. Early deceleration
Early decelerations start when uterine contraction begins & recover when
uterine contraction stops
This is due to increased fetal intracranial pressure causing increased vagal
tone
It therefore quickly resolves once the uterine contraction ends & intracranial
pressure reduces
This type of deceleration is therefore considered to be physiological .
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DR C BRAVADO

28. Decelerations
2. Variable Decelerations:
Variable decelerations are seen as a rapid fall in baseline rate with a variable
recovery phase.
They are variable in their duration & may not have any relationship to uterine
contractions
They are most often seen during labor & in patients with reduced amniotic fluid
volume
Variable decelerations are usually caused by umbilical cord compression.
The umbilical vein is often occluded first causing an acceleration in response. Then the
umbilical artery is occluded causing a subsequent rapid deceleration.
When pressure on the cord is reduced another acceleration occurs & then the baseline
rate returns.
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 BRAVADO

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

30. Decelerations
3. Late deceleration
Late decelerations begin at the peak of uterine contraction & recover after the
contraction ends.
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:
Maternal hypotension
Pre-eclampsia
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 BRAVADO

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

32. O Warda 32

33. Decelerations
5. Sinusoidal Pattern
This type of pattern is rare, however if present it is very serious
It is associated with high rates of fetal morbidity & mortality
It is described as:
A smooth, regular, wave-like pattern
Frequency of around 2-5 cycles a minute
Stable baseline rate around 120-160 bpm
No beat to beat variability
A sinusoidal pattern indicates:
Severe fetal hypoxia
Severe fetal anaemia
Fetal/Maternal Hemorrhage
Immediate C-section is indicated
for this kind of pattern. Outcome is usually poor
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DR C BRAVADO

34. Overall 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:
Reassuring
Suspicious
Pathological
-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 BRAVADO

35. Overall impression
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DR C BRAVADO

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 auscultation should occur
after a contraction, for a minimum of 60 seconds, and 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. O Warda 37
NICE 9- 2007

38. INTRAPARTUM FETAL MONITORING
Continuous EFM In Low-risk Women:
Evaluation :
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:
Augmentation
Perinatal mortality
Other neonatal morbidities
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NICE 9- 2007

39. O Warda 39