1. Basics of CTG Dr G Shree Lakshmi MS, MRCOG
Rangadore Memorial Hospital ,Bangalore

2. Learning objectives What? Why? When? How?
Terminology-Features& classification
Limitations
Legal issues

3. Cardiotocography A continuous recording of the fetal heart
rate and uterine activities by electronic system.
Antepartum
Intrapartum

4. It’s a mode of assessing fetal wellbeing in labour
Aim of CTG
It’s a mode of assessing fetal wellbeing in labour
The basic principle of fetal intrapartum monitoring is to detect developing fetalhypoxia with the aim of preventing subsequent acidaemia and cell damage.

5. Why is it we need to known about fetal hypoxia?
Fetal hypoxia is a major cause for perinatal death, neonatal morbidity and neurodevelopmental disability.
It can lead to complex medico–legal consequences. 
ITS MAINLY ACIDOSIS WHICH HARMS THE FETUS

6. Why hypoxia in labour?
During labor, the fetus experiences episodes of reduced oxygen supply and even lower oxygen tension than the conditions in utero.
Even during theuncomplicated labor, the fetus undergoes a number of repeated periods with reduced oxygen supply, caused by the uterine contractions and the consequent reduction in uterine and placental blood flow.
These brief hypoxic episodes are usually well tolerated, as the fetus has several defense mechanisms helping it to cope with the impaired oxygenation if it is a low riskpregnancy

7. Screening for fetal hypoxia- Cases at risk
Obstetric H/O – IUGR, APH, Post term, reduced FM, multiple pregnancy, breech
Meconium stained fluid – reduced quantity
Intrauterine infection
Iatrogenic – use of oxytocin

8. Why CTG in low risk labours
Labour augumentation & use of epidural in low risklabours convert them to high risk …… which needs CTG
HENCE TO LEARN CTG???

9. By monitoring FHR in CTG- we trying to detect fetal hypoxia

10. HYPOXIA-FHR CHANGES??
The effect of hypoxia on the fetal brain is reflected on the changes in FHR pattern
Brain stem centres influence acceleration of FHR with movement
baseline variability is a reflection of the integrity of the autonomic nervous systems. These centres are sensitive to hypoxia, and changes in the FHR pattern may suggest hypoxia.
Hypoxia is the most important cause of fetal heart abnormality and is potentially dangerous.

11. Fetal Hypoxaemia ≠ Hypoxia ≠ Asphyxia ≠ HIE/ CP
Respiratory & metabolic acidosis

12. pH is a log scale of H+

13. pH is a log scale of H+

14. Types of Hypoxia Cardiotocography detects hypoxia Acute Chronic
Subacute
Evolving

15. How to do a CTG ?

16. Pre-requisites for EFM – Check machine
The date and time clocks on the EFM machine should be correctly set
Adequate paper
Trace of atleast 20 min required to interpret
Set paper speed to 1 cm/min
Trace should be labeled with the mother’s name, date and hospital number

17. Pre-requisites for EFM – Maternal
Check and note maternal pulse on trace
Identify FH using Pinard/ steth / Hand-held doppler before connecting cardio- transducer
If maternal /fetal tachycardia note temperature on trace.

18. Pre-requisites for EFM – Maternal
Propped-up / semi-recumbent
Left lateral
Tilted to either side with a 45 deg wedge
Never take a trace with mum flat on her back!!!

19. Document
Any intrapartum events that may affect the FHR should be noted contemporaneously on the EFM trace, signed and the date and
time noted
(e.g. vaginal examination, ARM, fetal blood sample, siting of an epidural, loss of contact)

20. Interpretation- 4 features
Baseline Variability Accelerations Decelerations
DEFINITIONS?

21. Each of these features have been divided as
Reaasuring
Nonreassuring
Abnormal

22. Baseline rate - Mean level of FHR (excluding accelerations and decelerations)
Reassuring bpm Non-reassuring 100 to 109† OR 161 to 180 Abnormal Below 100 OR Above 180
Observed over 5-10 minutes
Prematurity associated with higher FHR
Trend in baseline and absolute value important

23. Tachycardia>160BPM
Normal BPM
Bradycardia<100BPM

24. Baseline variability
The minor fluctuations on baseline FHR at 3-5 cycles p/m produces Baseline variability.
Examine 1 min segment and estimate highest peak and lowest trough.
Normal is more than or equal to 5 bpm.

25. Variability
Normal 5 to 25 between contractions Non-reassuring Less than 5 for 30 to 50minutes OR More than 25 for 15 to 25minutes Abnormal Less than 5 for more than 50minutes OR More than 25 for more than 25minutes OR Sinusoidal pattern for more than 10mins

26. 5 Beats above and 5 beats below
1 minute

27. EFM-Accelerations
Accelerations- transient increase in FHR of 15 bpm or more lasting for 15 sec.
Presence of FHR Accelerations have Good outcome.
Absence of accelerations on an otherwise normal CTG remains unclear.

28. Accelerations Normal 2 accelerations in a 20 minute trace “reactive”
Accelerations less frequent in active labour

29. 15 beats
15 seconds

30. EFM- Decelerations
Transient episodes of slowing of FHR more than 15bpm for more than 15 seconds

31. Decelerations
15 sec
15 beats

32. Types of decelerations
Early
Variable
Late

33. Describing decelerations
their timing in relation to the peaks of the contractions
the duration of the individual decelerations
whether or not the fetal heart rate returns to baseline
how long they have been present for
whether they occur with over 50% of contractions
the presence or absence of a biphasic (W) shape
the presence or absence of shouldering
the presence or absence of reduced variability within the deceleration

34. Early decelerations Uniform Repetitive Onset early in contraction
Return to baseline by end of contraction
Require head compression

35. Lag time

36. Early Decelerations

37. Late decelerations Uniform, repetitive
Slowing of FHR with onset mid-end of contraction
Nadir >20secs post contraction peak
End after contraction

38. Late Decelerations.
Repetitive late decels increases risk of Umbilical artery acidosis and Apgar score of less than 7 at 5 mins and Increased risk of CP.
15bpm for 15 seconds less in non-accelerative reduced variability trace

39. 42 weeks, P0, Reduced FM
Em LSCS, pH 7.23, Normal apgars

40. Fig 4 Late Decelerations

41. Variable decelerations
Variable and intermittent
Rapid onset and recovery
Time relationship to contractions variable
May be isolated
May resemble other decelerations

42. Concerning characteristics of variable decelerations
lasting more than 60seconds;
reduced baseline variability within the deceleration;
failure to return to baseline;
biphasic (W) shape;
no shouldering.

43. Fig 5 Variable Decelerations

45. FEATURE
DECELERATIONS
REASSURING
None or Early ,Variable decelerations with no concerning characteristics* for less than 90minutes
NON REASSURING
Variable decelerations with no concerning characteristics* for 90minutes or more OR
Variable decelerations with any concerning characteristics* in up to 50% of contractions for 30 minutes or more OR
Variable decelerations with any concerning characteristics* in over 50% of contractions for less than 30 minutes OR
Late decelerations in over 50% of contractions for less than 30 minutes, with no maternal or fetal clinical risk factors such as vaginal bleeding or significant meconium
ABNORMAL
Variable decelerations with any concerning characteristics* in over 50% of contractions for 30minutes (or less if any maternal or fetal clinical risk factors [see above]) OR
Late decelerations for 30minutes (or less if any maternal or fetal clinical risk factors) OR
Acute bradycardia, or a single prolonged deceleration lasting 3minutes or more

46. Prolonged deceleration
Abrupt fall in FHR lasting for
at least 60 seconds

47. Prolonged deceleration
Non-reassuring
seconds
Abnormal
>3 minutes

48. CLASSIFICATION OF CTG

49. Classification of CTG Features
Reassuring
Non- Reassuring
Abnormal
Baseline FHR
bpm
100 to 109† OR
161 to 180
Below 100 OR Above 180
Baseline variability
> 5 bpm to 25bpm
Less than 5 for 30 to 50minutes
OR More than 25 for 15 to 25minutes
Less than 5 for more than 50minutes OR More than 25 for more than 25minutes OR Sinusoidal
Acceleration
Present

50. FEATURE
DECELERATIONS
REASSURING
None or Early ,Variable decelerations with no concerning characteristics* for less than 90minutes
NON REASSURING
Variable decelerations with no concerning characteristics* for 90minutes or more OR
Variable decelerations with any concerning characteristics* in up to 50% of contractions for 30 minutes or more OR
Variable decelerations with any concerning characteristics* in over 50% of contractions for less than 30 minutes OR
Late decelerations in over 50% of contractions for less than 30 minutes, with no maternal or fetal clinical risk factors such as vaginal bleeding or significant meconium
ABNORMAL
Variable decelerations with any concerning characteristics* in over 50% of contractions for 30minutes (or less if any maternal or fetal clinical risk factors [see above]) OR
Late decelerations for 30minutes (or less if any maternal or fetal clinical risk factors) OR
Acute bradycardia, or a single prolonged deceleration lasting 3minutes or more

51. Classification of CTG Traces
NORMAL
All 4 features reassuring
SUSPICIOUS
1 non-reassuring
3 reassuring features
ABNORMAL
2 or more non-reassuring or
1 or more abnormal

52. Rate-normal Variability-normal Deceleration-none Acceleration-yes
Classification-Normal
BLORE RCOG TRUST

53. SUSPICIOUS Rate-150bpm Variability-10bpm Deceleration-variable
Acceleration-?
SUSPICIOUS
BLORE RCOG TRUST

54. Deceleration-late
Abnormal
BLORE RCOG TRUST

55. Management based on interpretation of CTG traces

56. Category
Definition
Management
Normal
All features are reassuring
Continue CTG and usual care

57. Category
Definition
Management
Suspicious
1 non-reassuring feature AND 2 reassuring features
Correct any underlying causes, such as hypotension or uterine hyperstimulation
Perform a full set of maternal observations
Start 1or more conservative measures*
Document a plan for reviewing the whole clinical picture and the CTG findings
Talk to the woman and her birth companion(s) about what is happening

58. Category
Definition
Management
Pathological
1 abnormal feature OR 2 non-reassuring features
Exclude acute events (for example, cord prolapse, suspected placental abruption or suspected uterine rupture)
Correct any underlying causes, such as hypotension or uterine hyperstimulation
Start 1or more conservative measures*
If the cardiotocograph trace is still pathological after implementing conservative measures:
obtain a further review by an senior obstetrician
offer digital fetal scalp stimulation and document the outcome
If the cardiotocograph trace is still pathological after fetal scalp stimulation:
consider fetal blood sampling
consider expediting the birth
take the woman's preferences into account

59. Need for urgent intervention
Acute bradycardia, or a single prolonged deceleration for 3minutes or more
Urgently seek obstetric help
If there has been an acute event (for example, cord prolapse, suspected placental abruption or suspected uterine rupture), expedite the birth
Correct any underlying causes, such as hypotension or uterine hyperstimulation
Start 1or more conservative measures*
Make preparations for an urgent birth
Talk to the woman and her birth companion(s) about what is happening
Expedite the birth if the acute bradycardia persists for 9minutes
If the fetal heart rate recovers at any time up to 9minutes, reassess any decision to expedite the birth, in discussion with the woman

60. Conservative Measures
Encourage the woman to mobilise or adopt an alternative position (and to avoid being supine);
Offer intravenous fluids if the woman is hypotensive;
Reduce contraction frequency by reducing or stopping oxytocin if it is being used
And/or offering a tocolytic drug (a suggested regimen is subcutaneous terbutaline 0.25mg).

61. Can we detect hypoxia in time? Can we detect hypoxia reliably?
STRENGHTS & WEAKNESS OF
INTRAPARTUM SURVEILLANCE
Can we detect hypoxia in time? Can we detect hypoxia reliably?

62. EFM- Facts ? Affordability
Reliability of interpretation-50-75% are false positive
Sensitive in detecting abnormalities of fetal heart rate (FHR)
Specificity for detection of fetal hypoxia is low
False positive Dx reduces with FBS.
FBS 93% sensitivity, 6% false positive
? Affordability

63. Reliability of CTG Interpretation
50%-75% false positive
False Positive Dx is reduced to 10% with FBS
PH Vs lactate 39% Vs 2.3%(rr16.79)
Negative predictive value high

64. Inter-Observer Variation
5 clinicians, 100 parturients
•Traditional intrapartum evaluation: reassuring vs. nonreassuring
•46% of these patients had an emergent C/S
•2% had a fetal pH less than 7.0
•Study found poor inter-rater reliability and they could not predict which parturient had an emergency C/S or low pH!
Chauhan SP, Klauser CK, Woodring TC, Sanderson M, Magann EF, Morrison JC. Intrapartum nonreassuring fetal heart tracing and prediction of adverse outcomes: Interobserver variability. Am J Obstet Gynecol. 2008;199(6):623.e1-e5.

65. Perinatal asphyxia
Birth asphyxia that is severe enough to cause severe hypoxic ischaemic encephalopathy should have the following:
profound umbilical artery metabolic acidaemia defined as a
pH < 7.0
persistence of a low Apgar score < 3 for more than 5minutes
abnormal neurological signs during the neonatal period
evidence of hypoxic damage to other body systems such as
cardiovascular, pulmonary, gastrointestinal, renal and haematological system
ACOG 1992
International Cerebral palsy Task Force 1999

66. Cardiotocography (CTG) Facts
Remains the predominant method of intrapartum fetal monitoring
Main documentary evidence in medico-legal cases related to intrapartum hypoxia and birth asphyxia

67. Contributors To Adverse Perinatal Outcomes
Inability to interpret traces
failure to incorporate the clinical situation
delay in taking appropriate action
poor team working – communication lag

68. In Utero Diagnosis Of Fetal Hypoxia?
Hypoxaemia -> Hypoxia-> Asphyxia
Consider
Clinical picture re-physiological reserve (IUGR,APH,PT, meconium etc.)
Rate of progress of labour – parity, contractions, oxytocin, partogram
Diagnosis of hypoxia > Asphyxia – additional methods pH, lactate
Resuscitative measures> no improvement > delivery

69. THANK YOU