CTG
The trace should be read by the Mnemonic DR. C BRAVADO
DR - Define Risk -? Pre-eclampsia, diabetes, IUGR, smoker etc
C - Contractions - in the 2nd stage of labour - ideally <5 contractions in 10
minutes
BRA - Baseline rate - 110-160bpm
V - Variability - 5- 25 beats
A - Accelerations - 2 in 20 minutes
D - Decelerations - abnormal
O - Overall risk
FEATURES OF CTG
1. Baseline heart Rate
2. Baseline Variability (BLV)
3. Accelerations
4. Decelerations
NICHD 2008 Workshop On Electronic Fetal Monitoring
Baseline heart Rate
•
Mean FHR in increments of 5 bpm during 10 min tracing segment , excluding:
 Periodic / Episodic changes.
 Periods of marked FHR variability
 Baseline that differs > 25 bpm
Bradycardia : Boderline – 100-109bpm
Abnormal - <100 bpm
Tachycardia : Boderline – 161 -180 bpm
Abnormal term fetus- > 180 bpm
preterm fetus- >190 bpm
Variability
 Baseline - minimum of 2 min in any 10 min segment.
 Fluctuations in the FHR 2 cycles per min / greater.
 Variability is visually quantified as amplitude of peak to trough in bpm.
Absent
---- Undetectable amplitude range
Minimal
---- Detectable amplitude range < 5 bpm
Moderate
---- Amplitude range 6 – 25 bpm { Normal}
Marked
---Amplitude range > 25bpm (Saltatory pattern- Rapidly recurring
couplets of acceleration and deceleration causing relatively large oscillations of the baseline
fetal heart rate– It is not abnormal)
Sinusoidal pattern differs from variability. It is seen as a regular oscillation of the
baseline resembling a sine wave with 3-5cycles/mt and an amplitude of 5-15 above
and below the baseline,lasting atleast ten minutes.The baseline variability is absent
Etiology of sinusoidal pattern
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Anaemia(rhesus disease, haemoglobinopathies, FMH, vasapraevia)
Cord compression
Hypovolemia
Idiopathic(thumb sucking)
Drugs
Abruption
Accelerations

Visually apparent increase : onset to peak < 30 sec in the FHR from the
most recently calculated baseline.

Duration : Time from initial change in FHR from baselineto the return of the
FHR to the baseline.
< 32 wks :
> 10 bpm , > 10 sec ,< 2 min
> 32 wks :
> 15 bpm , > 15 sec ,< 2 min
Prolonged Acceleration > 2 min , < 10 min
If it lasts for > 10 min, it is baseline change/shift.
Decelerations
Early Deceleration:
 With uterine contraction, a visually apparent, usually symmetrical, gradual onset to
nadir > 30 sec – decrease in FHR of 15 bpm with return to baseline before end of
contraction.
 Nadir of deceleration occurs at the same time as peak of contraction.
Late Deceleration:
 With a uterine contraction , a visually apparent , gradual onset to nadir > 30 sec
decrease in FHR of 15 bpm with return to baseline.
 Onset, nadir and recovery of the deceleration occur after the beginning ,peak , and
end of the contraction ,respectively.
 Shallow deceleration - <15bpm is detrimental when associated with reduced baseline
variability
Variable Deceleration:
 An abrupt onset to nadir < 30 sec, visually apparent decrease in the FHR below the
baseline.
 The decrease in FHR is > 15 bpm , with a duration of > 15 sec but < 2 min.
Shouldering – suggestive of well compensated fetus
Atypical variable decelaration :
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Deceleration to <70bpm lasting >60sec
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Loss of variability in the baseline FHR and in the trough of the deceleration
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Biphasic decelerations
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Prolonged secondary acceleration (post deceleration overshoot of >20bpm & / or
lasting 20 sec)
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Slow return to baseline
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Continuation of the baseline at a lower level after the deceleration
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Associated fetal tachycardia
Prolonged Deceleration:
 Visually apparent decrease in the FHR below the baseline.
 Deceleration is > 15 bpm , lasting > 2min but < 10 min from onset to return to
baseline.
Reassuring
Non
reassuring
Abnormal
Categorisation of features
If fetal blood sampling is not possible, the baby should be delivered as soon as possible
based on the clinical circumstances of the CTG.
Contraindications for FBS:
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Clear evidence of severe fetal compromise
Fetal bleeding disorders
Maternal infection (Herpes, HIV, Hepatitis etc.)
< 34 weeks gestation
Face presentation