isamaldin CTG MBBS student

1. Fetal cardiotocography
CTG
Dr Isameldin Elamin MD DOWH MBBS
Assistant Professor
Obstetrics & Gynaecology

2. By the end of this lectures Student should be able:
 To recognize different part of CTG.
 To describe how CTG works.
 To discuss the maternal risks which need
electronic fetal monitoring.
 To read and interpret the CTG.
Objectives

3. Cardiotocography (CTG) is a technical means
of recording (-graphy) the fetal heartbeat (cardio-
) and the uterine contractions (-toco-) during
pregnancy.
The machine used to perform the monitoring is
called a Cardiotocograph, more commonly
known as an Electronic Fetal Monitor (EFM).
Introduction

4.  Changes in FH rate patterns occur in
response to changes in O2, CO2, hydrogen
ions and arterial pressure
 These changes are mediated via the vagus
nerve, chemoreceptors & carotid body
baroreceptors
Pathophysiology of FH rate changes

5.  It is difficult to measure fetal oxygenation
and pH continuously
 FH rate patterns only allow indirect
assessment of fetal acid-base balance.
 Fetal scalp sampling is required to confirm
whether the fetus is hypoxic…
Pathophysiology of FH rate changes

6.  The heart rate of the fetus is calculated
using a Doppler ultrasound transducer.
 signals detected are cardiac movement.
 what is actually measured is the time
interval between cardiac cycles. this is converted
to heart rate.
Principle of CTG

7. CTG monitors:
 Fetal heart rate (FHR).
 uterine contractions.
prints on a two-channel strip chart recorder.
Principle of CTG…CONT.

8. CTG obtained by:
 external transducers that are placed on the
maternal abdomen.
 Internal monitoring by:
spiral electrode onto the fetal scalp.
plastic catheter transcervically to monitor
uterine contractions.
Principle of CTG…CONT.

9. 2 electrode
one for FHR
One for uterine contraction

10. for FHR on lower abdomen
for uterine contraction on upper abdomen

11. CTG machine and paper

12. CTG probes
Feto and toco

13. Setting CTG machine speed 1cm or 2 or 3 cm per minute

14. Internal monitoring

15. CTG trace showing Uterine contraction and fetal heart rate

16. Perinatal outcomes
 50% reduction in neonatal seizures
… but no difference in incidence of:
- long-term neurological handicap
- or perinatal mortality.
Obstetric outcomes
 66% increase in Caesarean section rate
 16% increase in instrumental delivery
CTG: Aim & out comes

17. CTG Should be reserved for high risk
pregnancies.
(CTG) is the accepted standard for:
 intra-partum fetal monitoring in women with
additional risk factors.
 Non-sterss test (NST) for fetal monitoring in
women not in labour.
CTG: Aim & out comes

18. Fetal risks:
 Intrauterine growth restriction
 Oligohydramnios
 Abnormal Doppler velocimetry
 Preterm labour
 Multiple pregnancy
 Breech presentation
 Rhesus iso-immunisation
Risk factors

19. Maternal risks:
 Previous Caesarean section
 Pre-eclampsia
 Pregnancy >42 weeks
 Prolonged ROM >24 hours
 Diabetes
 Antepartum haemorrhage
 Significant medical condition – eg cardiac
Risk factors CONT.

20.  Meconium stained liquor.
 Abnormal FHR on auscultation
 Tachycardia
 Decelerations.
 Maternal pyrexia
 38°C once
 or 37.5°C on 2 occasions 2 hours apart
 Fresh bleeding in labour
 Oxytocin augmentation
Changing from low risk to high risk

21.  Many school for interpretation of CTG
 NICE, ACOG, ALSO, others
 All Through the following features:
 Basal heart rate (BHR).
 Beat to beat variability.
 Accelerations.
 Decelerations.
 Uterine contractions.
CTG reading and interpretation

22.  Letters to make reading CTG more easy.
 Determine Risk
 Assess degree of “clinical risk” in relation to perinatal
outcomes
 Low
 Medium
 High
DRCBRAVADO

23.  Uterine Contraction
 BASE LINE HEART RATE
 ACCELERATIONS
 VARIABILITY
 DECELERATIONS
 OVER ALL ASSESSMENT
DRCBRAVADO….cont.

24. Baseline Fetal Heart Rate

25.  Must be >15 bpm and >15 sec above baseline
 Should be >2 per 15 min period
 Always reassuring when present
 May not occur when fetus is “sleeping”
 Should occur in response to fetal movements or
fetal stimulation
 Non reactive periods usually do not exceed 45
min
 (>90 min and no accelerations is worrying)
Accelerations

26. Accelerations

27.  It is the most important feature of any CTG
 Is a reflection of competing acceleratory and
decelerating CNS influences on the fetal heart
 And therefore represents the best measure of CNS
oxygenation, so its absent may indicate CNS
hypoxia
Variability

28.  Absent – undetectable
 Minimal less than or equal to 5bpm
 Moderate 6 to 25 bpm
 Marked greater than 25 bpm
 Will be affected by drugs and fetal sleeping
cycles
 Will be reduced in the pre term fetus and
congenital heart abnormalities
Variability…CONT.

29. variability
Reduced Normal

30. Variability

31.  Early: mirrors the contraction
Typically occurs as the head enters the
pelvis and is compressed, i.e. it is a vagal
response
 Late: Follows every contraction and exhibits a
slow return to baseline
Uncommon, the response of a hypoxic
myocardium
Uteroplacental insufficiency
Decelerations

32.  Variable: Show no relationship to
contractions
Variable shape, onset and duration
Umbilical cord compression
 In practice many decelerations are MIXED
CONT..

33. Early deceleration

34. Early Deceleration

35.  Associated with fetal compromise (hypoxia)
but only in 50-60% of cases
 Ominous if associated with:
- fresh particulate meconium
- ‘high-risk’ clinical situation
 Ominous if:
-  ‘lag-time’ (peak to trough)
- deceleration is slow to recover
Beware of SHALLOW, DELAYED decelerations
Late Decelerations

36. Late Decelerations

37. Late Decelerations
• Begin after onset of
contraction
• Nadir (or trough) after
peak of contraction
• Return to baseline after
end of contraction

38. Late Decelerations

39. Early vs. late decelerations

40.  Most decelerations in labour are variable
 Can reflect cord compression
 ‘Variable’ in shape, depth and/or onset
 Usually benign but …. if late or deep may
imply cord prolapsed or hypoxia
 ‘Shoulders’ before and/or after ( )
are amore benign feature
 Need to assess the frequency and duration
Variable Decelerations

41. Variable decelerations

42. Variable decelerations

43.  Smooth undulating, sine wave pattern
 Defined by an amplitude of 10bpm in cycle of two
to five per minute, lasting at least two minutes.
 May be a terminal pattern -severe hypoxia
 Associated with severe fetal anaemia, hydrops
and fetomaternal haemorrhage.
 False sinusoidal pattern not uncommon,
particularly if intermittent and with normal
variability
 In a true sinusoidal pattern variability is absent
Sinusoidal pattern

44. Sinusoidal pattern

45. Sinusoidal pattern

46. Prolonged deceleration

47. CTG- Twins

48. CTG- Late deceleration+ decreased variability
example:

49.  Frequency = no. in 10 minutes
 Duration of each contraction
 Interval = between end of one and starting of the next contraction
 More than 5/10 min= tachysystole
 Intensity- can not be directly measured by external CTG
Uterine contractions

50.  Cord compression=variable deceleration.
 Head compression=early deceleration.
 Placental insufficiency= late deceleration
Remember

51. CTG Interpretation

52.  No decision on the basis of (CTG) findings
alone.
 Take into account:
 risk factors.
 woman.
 unborn baby
 progress of labour.
Overall care

53.  Care remains on the woman rather than the CTG
trace.
 Remain with the woman at all times.
 Assessment of woman and baby hourly, or more
frequently if there are concerns.

54.  Assess and document all 4 features.
 Not possible to categorise every CTG trace.
 Accelerations is a sign that the baby is healthy.
 If fetal blood sample cannot be obtained, but
results in accelerations, decide according to
clinical circumstances and in discussion with the
woman.
Principles for CTG interpretation

55.  Baseline FHR (beats/ minute).
 Baseline variability (beats/ minute).
 Decelerations.
 Acceleration
CTG Features

56.  Normal/ reassuring.
 Non-reassuring.
 Abnormal.
Description of Features

57.  CTG is normal/reassuring.
healthy fetus
 CTG is non-reassuring.
increased risk of fetal acidosis
Suggest conservative measures.
CTG Categories

58.  CTG is abnormal
more likely associated with fetal acidosis
indicate conservative measures
Further testing.
 CTG is abnormal needs urgent intervention.
 very likely to be associated with current
fetal acidosis

59.  100-160
normal/reassuring.
 161–180 Non-
reassuring.
 Above 180 or below 100. Abnormal.
Baseline FHR (beats/ minute)

60.  5 or more. normal/reassuring.
 less than 5 for 30–90 minutes. Non-
reassuring.
 Less than 5 for over 90 minutes. Abnormal.
Baseline variability (beats/minute).

61.  Normal/reassuring.
None or early deceleration.
Decelerations

62. Non-reassuring:
 Variable decelerations:
 dropping = < 60 beats for 60 seconds or
less.
over 90 minutes
over 50% of contractions
deceleration

63.  Variable decelerations:
more than 60 beats
or taking over 60 seconds.
present for up to 30 minutes
over 50% of contractions

64.  Or Late decelerations:
present for up to 30 minutes
occurring with over 50% of contractions

65.  Abnormal deceleration:
 Non-reassuring variable decelerations
after conservative measures for 30 minutes.
with over 50% of contractions.

66.  Late decelerations
for over 30 minutes
not improve with conservative measures.
with over 50% of contractions.
 Bradycardia or a single prolonged deceleration
lasting 3 minutes or more

67.  CTG is normal/reassuring:
All 3 features are normal/reassuring.
 CTG is non-reassuring and suggest need
conservative measures:
1 non-reassuring+2 normal/reassuring features
Interpretation of CTG
or CTG categories

68.  CTG is abnormal and indicate need for
conservative measures and further testing
1 abnormal Feature
OR 2 non-reassuring features

69.  CTG is abnormal and indicate needs for urgent
intervention:

 Bradycardia.
 a single prolonged deceleration with
baseline below 100 beats/minute, persisting
for 3 minutes or more

70.  Continue CTG and normal care.
 remove CTG after 20 minutes if normal and
no risk factors
If CTG is normal/reassuring:

71. If fetal heart rate is over 160 beats/minute
 check temperature and pulse
 give fluids and paracetamol.
Start 1 or more conservative measures:
 mobilise and left-lateral position
 intravenous fluids
 stopping oxytocin offering tocolysis.
Inform midwife and obstetrician.
CTG is non-reassuring

72.  If fetal heart rate is over 180 beats/minute
 check temperature and pulse
 give fluids and paracetamol.
 Start 1 or more conservative measures:
 mobilise
 left-lateral position
 intravenous fluids
 stopping oxytocin
 offering tocolysis.
 Inform midwife and obstetrician
CTG is abnormal + conservative
measures +testing

73.  Offer FBS after conservative measures.
 expedite birth if:
 FBS cannot be obtained
 no accelerations.
 Take action sooner than 30 minutes if:
 late decelerations + tachycardia +reduced
variability.
 Inform and discuss with the consultant if:
 FBS result is abnormal.
 FBS cannot be obtained
 third FBS is thought to be needed.

74.  Start conservative measures.
 Inform midwife and obstetrician
 Urgently seek obstetric help
 Make preparations for urgent birth
 Expedite birth if persists for 9 minutes
 If heart rate recovers before 9 minutes, reassess
decision to expedite birth in discussion with the
woman.
CTG is abnormal + urgent intervention

75. Classification of fetal blood sample
results

76.  Normal: offer repeat after 1 hour.
 Or sooner if additional non-reassuring or
abnormal features are seen.
 Borderline: offer repeat sampling in 30 minutes.
 Or sooner if additional non-reassuring or
abnormal features are seen.

77.  Discuss with the consultant obstetrician if:
 a fetal blood sample cannot be obtained or
 a third fetal blood sample is thought to be
needed.

78. Description FHR variability Decelerations
Normal/reassuring 100–160 5 or more None or early
Nonreassuring 161–180 less than 5
for 30–90 minutes
Variable decelaration:
drop=<60 beats recover=<60 seconds for 90
minutes.
Drop>60 beats recover>60 seconds up to 30
minutes.
Late decelerations:
present for up to 30 minutes
Abnormal Above 180
or
below 100
Less than 5
for > 90 minutes
Still Non-reassuring for 30 minutes after
conservative.
Late decelerations >30 minutes
not improve with conservative.
Bradycardia or deceleration =>3 minutes.
Conclusion CTG features

79. CTG Category Definition Interpretation Management
normal/reassuring 3 features are
normal/reassuring
Healthy fetus Remove CTG after 20
minutes
Non-reassuring 1 non-reassuring
feature
risk of fetal acidosis conservative measures
Abnormal :
need for conservative
measures AND further
testing
1 abnormal
OR
2 non-reassuring
features
fetal acidosis more
likely
conservative measures
FBS
Abnormal:
need for urgent
intervention
Bradycardia
single prolonged
deceleration for 3
minutes
current fetal
acidosis
conservative measures
make preparations for urgent
birth
Conclusion CTG trace interpretation

80. Variable deceleration
decreased variability
CTG categary:
Abnormal : need for conservative measures AND further testing
FBS needed

81. Bradycardia
CTG is abnormal and indicate needs for urgent intervention

82. Normal CTG with acceleration

85.  variable decelerations with the V-shaped picture are a
normal, reflex response to umbilical cord compression.

86. A preeclamptic patient at 33 weeks gestation with IUGR is undergoing induction of
labor. The fetal heart rate tracing shows evidence of uteroplacental insufficiency
and is nonreassuring.

87. A 23-year-old G1P0 at 42 weeks is undergoing induction of labor. She is receiving
intravenous oxytocin. She complains that her contractions are very painful and seem
to be continuous.

88. A patient at 41 weeks is undergoing NST. Her NST is reassuring.

89.  Interpretations of CTG in uptodate:
 Category1=normal CTG
 Category2=nonreassuring.
 Category3=abnormal.
Uptodate and ACOG

90.  intrapartum care: nice guideline cg190
(december 2014)
 essentials of obstetrics & gynaecology
hacker & moore, fifth edition
 obstetrics by ten teachers 19 editions.
 http://www.uptodate.com.
Further reading

91. THANK YOU