This document discusses various patterns seen on cardiotocography (CTG) monitoring of fetal heart rate. It describes normal baseline heart rate ranges and variability. It also defines different periodic changes seen such as accelerations and decelerations including early decelerations, late decelerations, variable decelerations and prolonged decelerations. Various abnormal patterns are also described such as tachycardia, bradycardia, reduced variability and sinusoidal patterns. Causes and clinical significance of these findings are discussed.

1. CTG: patterns
Aboubakr Elnashar
Benha University Hospital, EgyptAboubakr Elnashar

2. I. Basal Heart Rate Activity
1. Rate:
 Normal:110-160 increment 5 bpm (10 m segment)
 Bradycardia: < 110 bpm
 Tachycardia: > 160bpm
2. Variability
 Short term= instantaneous (beat to beat v.)
 Long term= oscillatory changes in 1 m
3. Sinusoidal:
 Mild is due to sedation
 Marked is due to fetal anemia
4. Arrhythmia:
Abrupt spiking, bradycardia or tachy
II. Periodic heart rate Activity
1. Acceleration
2. Deceleration
 Early
 Late
 variable
 prolonged
Aboubakr Elnashar

3. I. Baseline
Tachycardia
Baseline FHR > 160 bpm
Bradycardia
Baseline FHR < 110 bpm
Aboubakr Elnashar

4. 1. Normal
FHR in ten beat
intervals ranging
from 30 bpm to
240 bpm.
Normal FHR is 110
to 160 bpm
1. RATE
Aboubakr Elnashar

5. The mean FHR
rounded to increments of 5 bpm during a 10-min
segment, excluding:
— Periodic or episodic changes
— Periods of marked FHR variability
— Segments of baseline that differ > 25 bpm
Aboubakr Elnashar

6. Determining the Baseline
Each red line indicates a 2 minute
In any 10 minute segment, the minimum baseline
duration is 2 minutes within the 10 minute segment.
Baseline Rate: 130/m
Aboubakr Elnashar

7. 2. Tachycardia:
FHR ≥160bpm
Fetal tachycardia with fetal
arrhythmia
Severe
tachy
Aboubakr Elnashar

8. Uncomplicated baseline tachycardia:161-180 bpm:
Not associated with poor NN outcome.
Mild
Aboubakr Elnashar

9.  Common Causes of Fetal Tachycardia
Maternal
1. Fever/infection (Amnionitis)
2. Anxiety
3. Drugs:
Anticholinergic: Atropine
Beta sympathomimetic:
Terbutaline
Illicit: Cocaine,
Methylamphetamines
Fetal
1. Hypoxia
2. Anemia
3. Cardiac arrhythmias
Aboubakr Elnashar

10. 3. Bradycardia: baseline FHR ≤110 bpm
• Mild: 100 –110 bpm
• Moderate: 80-100 bpm
• Severe: < 80 bpm
Mild: not associated with poor neonatal outcome.
Prolonged: FHR < 100/ min for 3 min or
< 80 for 2 min
Aboubakr Elnashar

11. Causes of bradycardia
Aboubakr Elnashar

12. 2. VARIABILITY
Changes in the FHR
{interaction of the sympathetic and parasympathetic
systems of the fetus}.
Define:
 Fluctuations in the FHR of more than 2 cycles
pm or greater
 Amplitude=distance between the highest point
and the lowest point of each of the fluctuation
 These fluctuations are irregular in amplitude and
frequency.
 The baseline must be for a minimum of 2 min in
any 10-min segment
Aboubakr Elnashar

13. Types
1. Short term:
 Change of FHR from one beat to the next
 [Time between cardiac systoles]
 in internal fetal scalp electrode
2. Long term:
 Oscillation of FHR around baseline /min
 [2-6 cycles or waves/min]
Aboubakr Elnashar

14. long-term beat-to-beat variability
ranging between 125 and 135 bpm.
Defined as 3-5 cycle/min
Aboubakr Elnashar

15. Quantification=degrees
1. Absent:
amplitude range undetectable
2. Minimal:
amplitude range detectable but 5 bpm
3. Moderate (normal):
amplitude range 6–25 bpm
4. Marked:
amplitude range > 25 bpm
What is FHR baseline?
Whether variability exists?
What is Degree?
Aboubakr Elnashar

16. To calculate variability you look at how much the peaks &
troughs of the HR deviate from the baseline rate (in bpm)
≥ 25 bpm amplitude range
Aboubakr Elnashar

17. (1) Undetectable or absent
(2) Minimal variability:0 -5 bpm
Aboubakr Elnashar

18. 4) Marked variability: >25 bpm
(3)Moderate variability: >5-<25 bpm
Aboubakr Elnashar

19. A. lack of long-term variability
at 31 w during maternal
diabetic ketoacidosis (pH
6.09).
B. Recovery of fetal long- term
variability after correction of
maternal acidemia.
Aboubakr Elnashar

20. Abnormal base line variability
Absent:
Amplitude range is undetectable
Minimal:
Amplitude range ≤5bpm
Moderate:
Amplitude range is 6-25bpm
Marked:
Amplitude range is >25 bpm
Aboubakr Elnashar

21. Aboubakr Elnashar

22. Aboubakr Elnashar

23. Causes of Reduced variability
single most reliable sign of fetal compromise
• Foetus sleeping:
should last no longer than 40 min
most common cause
• Foetal acidosis {hypoxia}
more likely if late decelerations also present
• Foetal tachycardia
• Drugs:
Opiates
Benzodiazipine’s
Methyldopa
Mg sulphate
• Prematurity:
variability is reduced <28 w
• Congenital heart abnormalitiesAboubakr Elnashar

24. 3. SINUSOIDAL HEART RATE
Define:
– Regular Oscillation of the Baseline long-term
Variability
– Resembling a Sine wave, with no BTBV.
– Amplitude: 5-15bpm
– 2- 5 cycle/m
– Absence of accelerations
Aboubakr Elnashar

25. •Sinusoidal pattern associated with maternal IV meperidine
administration.
•Sine waves are occurring at a rate of 6 cycles/min.
Aboubakr Elnashar

26.  Causes
• Mild:
due to sedation
• Marked:
due to fetal anemia associated with:
• Rh isoimmunization
• Fetal hypoxia
• Chronic fetal bleeds
• Fetal-maternal hge
• Severe acidosis
PSEUDOSINUS
Aboubakr Elnashar

27. II. Periodic heart rate Activity
Periodic changes:
accelerations or decelerations in FHR that occur in
direct association with uterine contractions.
Episodic (sporadic) changes:
accelerations or decelerations FHR that occur
independent of uterine contractions, in response to
vaginal exam
maternal vomiting
fetal movement
Aboubakr Elnashar

28. Acceleration
Periodic acc Sporadic acc
15bpm 15 sec
<32wks= 10 -10
Acceleration
Aboubakr Elnashar

29. 1. ACCELERATION
Define:
An increase in the FHR from the most recently
calculated baseline
Onset to peak:
less than 30 sec
The duration
Time from the initial change in FHR from the
baseline to the return of the FHR to the baseline
less than 2 minutes
Prolonged acceleration
lasts 2 min, but < 10 min
Baseline change
If an acceleration lasts 10 min
Aboubakr Elnashar

30. Aboubakr Elnashar

31. Adequate accelerations:
>32 w
An acme: 15 bpm above baseline
Duration: 15 sec but < 2 min
< 32 w
An acme: 10 bpm above baseline
Duration: 10 sec but < 2 min
< 28 w
Amplitude of accelerations: lower than a
fetus ≥ 32w.
FHR baseline: higher
Variability: less
Aboubakr Elnashar

32. Significance
 Presence:
 at least 2 accelerations/15 m
 Reassuring
 Sign of a healthy foetus
 Absence with an otherwise normal CTG:
uncertain significance
Aboubakr Elnashar

33. Aboubakr Elnashar

34. 2. DECELERATION
1. Early deceleration
 Define:
In association with a uterine
contraction
Start when uterine contraction
begins
Recover when uterine
contraction stops
Symmetrical=Nadir occurs at the
same time as the peak of the
contraction
Gradual=Onset to nadir:
30 sec or more
Aboubakr Elnashar

35. Gradual decrease
in HR
Both onset and
recovery coincident
with the onset and
recovery of the
contraction.
Onset to Nadir:
30 seconds or more.
Aboubakr Elnashar

36. Significance
 Physiological & not pathological
{increased foetal intracranial pressure causing increased
vagal tone}
 Quickly resolves once the uterine contraction ends &
intracranial pressure reduces
 May be prevented by avoiding early ROM
Mirror Image
Aboubakr Elnashar

37. 2. Late deceleration
Define:
In association with a uterine contraction
Gradual=onset to nadir 30 sec or more
decrease in FHR with return to baseline
Onset, nadir, and recovery of the deceleration
occur after the beginning, peak, and end of the
contraction, respectively
Aboubakr Elnashar

38. Late deceleration.
Gradual decrease in the HR
Nadir and recovery occurring after the end of the contraction.
Nadir of deceleration occurs 30 seconds or more after the
onset of the deceleration.Aboubakr Elnashar

39. •Late
decelerations
{uteroplacental
insufficiency
resulting from
placental
abruption}.
Immediate CS
•Umbilical artery
pH: 7.05
• Po2: 11 mm Hg.
Aboubakr Elnashar

40. Significance:
 uteroplacental insufficiency:
hypoxia and metabolic abnormalities.
 one of the most ominous FHR patterns
Aboubakr Elnashar

41.  Repetitive late deceleration:
increases risk of
 Umbilical artery acidosis
 Apgar score < 7 at 5 m
 Cerebral palsy
If associated with decrease or
loss of BBV
Aboubakr Elnashar

42. Aboubakr Elnashar

43. Aboubakr Elnashar

44. 3. Variable deceleration
Define:
Decrease in FHR of > 15 bpm measured from the most
recently determined baseline rate.
Abrupt=Onset to nadir: less than 30 seconds.
lasts > 15 sec and less than 2 min
onset commonly varying with successive contractions
may be v-shaped, u-shaped or w-shaped.
Aboubakr Elnashar

45. Aboubakr Elnashar

46. W-shaped
Aboubakr Elnashar

47. Aboubakr Elnashar

48. •Variable
decelerations
B ―shoulders‖ of
acceleration
compared with
deceleration A.
Aboubakr Elnashar

49. FHR effects of partial
occlusion and
complete occlusion of
the umbilical cord
Aboubakr Elnashar

50. • Pressure on the cord initially occludes the umbilical vein
acceleration (the shoulder of the deceleration): healthy
response.
• This is followed by occlusion of the umbilical artery sharp
down slope of FHR.
• Finally, the recovery phas {relief of the compression} 
sharp return to the baseline  another healthy brief
acceleration or shoulder
Variable deceleration with pre- and post-accelerations
(―shoulders‖). Aboubakr Elnashar

51. Significance
 depends upon
 how often they occur
 how deep they go
 how long they last.
 how the fetus responds in their presence.
 um cord compression
(Common: 50-80% 2nd stage)
Reassuring variable deceleration:
Abrupt (sharp) onset
Abrupt return to baseline
Preceded & followed by shoulders
Aboubakr Elnashar

52. Aboubakr Elnashar

53. Complicated variable decelerations:
Deceleration
Role of 60
depth >60 bpm
for >60 seconds
rate of 60 bpm
Changes in shape: over-shoot
Slow recovery
Baseline FHR:
Decreased or increased following the
decelerations
BBV:
Absent in or between decelerations
Aboubakr Elnashar

54. Re-assuring
a) Abrupt return to base
line
b) BBV: Normal
c) Initial acceleration
d) Secondary
acceleration
Non-reassuring(atypical)
a) Slow return to baseline
b) BBV: Loss during
deceleration
c) Loss of initial
acceleration
d) Persistent acceleration
after recovery
e) Continuation of base
line at low level
f) Biphasic deceleration
Aboubakr Elnashar

55. Atypical variable deceleration
Aboubakr Elnashar

56. 4. Prolonged deceleration
Define:
Decrease in the FHR below the baseline
Deceleration is 15 bpm
lasting 2 min but < 10 min from onset to return
to baseline
Aboubakr Elnashar

57. Prolonged deceleration
following uterine rupture
Prolonged deceleration
following vaginal exam
Aboubakr Elnashar

58. Significance:
• Non-Reasurring: lasts between 2-3 min
• Abnormal: lasts longer than 3 min it is
immediately classed as Action must be taken
quickly
e.g. FB sampling/emergency CS
Maternal
1. Hypotension
2. Hypoxia
3. Uterine
hyperactivity
4. Abruption
5. Uterine rupture
Fetal
1. Hypoxia
2. Fetal hemorrhage
3. Cord prolapse
4. Cord compression
Aboubakr Elnashar

59. Prolonged Deceleration
either Late or Variable
>90 sec & < 10 min,
Drop in FHR of 30 bpm or More
lasting for at least 2 m
Depth& duration
Correlate e Insult
Aboubakr Elnashar

60. Abrupt decrease
>15 bpm
Often drops<100
>2 m & < 10 m
Variable pattern
{uterine hyperactivity}
Approximately 3 min
are shown but FHR
returned to normal
after uterine
hypertonus resolved.
Vaginal delivery later
ensued.
Aboubakr Elnashar

61. Manual Compression of
a prolapsed umbilical cord
in a 25-w footling breech.
A. 25- sec compression
B. 40 sec compression
Aboubakr Elnashar

62. Early Deceleration
Late Deceleration
Variable Deceleration
Abrupt decrease
 >15 bpm
Often drops<100
>15 S& < 2 m
Variable pattern
Abrupt decrease
 >15 bpm
Often drops<100
>2 m & < 10 m
Variable pattern
Prolonged Deceleration
may drops<100
Usually did not drops<100
Decelerations
Aboubakr Elnashar

63. Thanks
Aboubakr Elnashar