Undergraduate level presentation on cardiotocography, basics of the topic is described.

1. Orangzeb Khatri
Final Year MBBS Student
Dow Medical college

2. › It is a procedure of recording (graphy) the fetal heartbeat
(cardio) and the uterine contraction (toco) on a graph.
› It is used to assess fetal wellbeing (O2 sat) along with
uterine contractions.
› The machine used to perform the monitoring is called a
cardiotocograph.

4. › The term Electronic Fetal Monitoring is sometimes used
instead of CTG monitoring, but is considered to be a less
precise term because :
› 1.CTG monitoring also includes monitoring the mother’s
contractions and
› 2.other forms of fetal monitoring might also be classed as
‘electronic’ e.g. fetal pulse oximetry

5. › CTG is obtained pregnant woman in left lateral/ semi-
recumbent position.
› Two external transducers are placed on mother’s
abdomen, one is pressure sensitive tocodynometer which
records uterine activity (Ctx), 2nd uses US to measures fetal
heart rate.
› Each of the transducers may be either externally or
internally. Mother may be given a button to press to
record fetal movement that she has felt
› It is recorded for at least 30 min
For twins an extra transducer is placed.

6. › The length of the CTG strip depends on the paper speed, it
is usually 1cm/min.
› Each vertical division on the paper is 1cm and therefore
1min.

7. › All cases of BOH i.e. previous still birth, asphyxia, low
Apgar, recurrent abortion, neonatal death.
› Risk of fetal hypoxia i.e. IUGR, postdate, hypertension,
induction of labour, prolonged labour
› Premium babies i.e. IVF, elderly, diabetic

8. › Uterine activity (contractions)
› Baseline fetal heart rate
› Baseline FHR variability
› Accelerations
› Decelerations

9. › Frequency: no: of contractions/min
› Duration: (x-axis)
› Intensity: (y-axis) with external monitoring use palpation to
determine relative strength.
› Resting Tone: how relaxed the uterus is between contractions.
› Interval: between contractions.

10. Assessed for at least 10 min
May be defined as:
› Normal: <5 contractions/10 minutes.
› Tachysystole: >5 contractions/10 minutes (tocolytics are
used)

12. › average heart rate of the fetus within a 10-minute window
in between uterine contractions
› Fetal heart rate is regulated by ANS, vasomotor,
chemoreceptor and baroreceptor mechanisms
› Normal heart rate at term is 110-160 bpm, <110 is
bradycardia >160 is tachycardia

13. › Tachycardia is caused by fetal hypoxia (early),
maternal/fetal infection/fever, tachyarrhythmias (SVTs),
thyrotoxicosis (m), prematurity, drugs: sympathomimetics
i.e. terbutaline, maternal anxiety, fetal movement.
› Bradycardia is caused by head compression, fetal hypoxia
(late), fetal heart block, drugs i.e. narcotics, epidurals,
oxytocin, maternal hypotension, cord compression.

15. › It is the normal fluctuations in the FHR that shows as an
irregular heart rate seen on the tracing instead of a
smooth line.
› B2B interval varies called short-term variability (not
detected on standard CTG) however, longer-term
fluctuations (2-6 times/m) are called Baseline Variability
› one of the most important indicators in the clinical
assessment of fetal well-being. Variability is indicative of a
mature fetal neurologic system (ANS)

16. › It varies with gestational age, fetal sleep and activity,
drugs which supress CNS i.e. opioids and hypnotics, fetal
infection, hypoxia
› 0= absent (requires immediate delivery)
› 1-5= minimal (hypoxia, narcotics, sleep, prematurity,
MgSO4, congenital heart abnormalities)
› 6-25= normal (PH >7.25)
› >25= marked (fetal hypoxia)
› Normally each variation is more than 10 bpm

18. › These are increases in the baseline FHR atleast 15 bpm
lasting for atleast 15 seconds.
› ≥2 accelerations in 20min intrapartum CTG defines a reactive
trace and shows a non hypoxic fetus (moving)
› Presence of accelerations is reassuring absence is concerning
may be due to hypoxia or drugs
› Accelerations occurring alongside uterine contractions is a sign
of a healthy fetus.
› The absence of accelerations with an otherwise normal CTG is
of uncertain significance.
› >2 <10 min= prolonged acceleration >10 min= increase in
baseline

20. › Transient reduction in FHR of atleast 15bpm lasting atleast
15 sec.
1. Periodic: associated with contractions
2. Episodic: not associated with contractions
>2 min <10 min= prolonged deceleration
It is caused by fetal hypoxia, cord compression etc. If
present should be correlated with other findings of hypoxia
i.e. no variability, bradycardia.

21. › THREE Types of Decelerations:
1 Early deceleration
2 Late deceleration
3 Variable deceleration

22. › begins at the onset of the contraction and ends with the
end of the contraction
› Uterine Contraction > ↑ ICP > ↓ CBF > vagal stimulation >
↓ FHR
› Frequently occur with 2nd stage of labour
› not a sign of fetal problem

24. › transitory decreases in heart rate caused by utero-
placental-insufficiency
› Uterine Contraction > decrease fetal blood flow > α
adrenergic response > ↑ BP > Baroreceptor response > ↓
FHR
› begins after the onset at peak or middle of the
contraction and ends after the contraction
› Persistent late decelerations are threatening, especially if
the decelerations are associated with loss of variability

25. Utero-placental-insufficiency due
› Maternal hypotension
› Pre-eclampsia
› Uterine hyperstimulation
› The presence of late decelerations is concerning and fetal
blood sampling for pH is indicated. If fetal blood pH is
acidotic it indicates significant fetal hypoxia and the need
for emergency C-section

27. › transitory decreases in fetal heart rate caused by cord
compression, unrelated to contractions
Which leads to UV compression > ↓ fetal BF > ↓ BP > ↑ FHR
If compression continues > UA compression > ↑ BP >
↓ FHR
› Variable decelerations are not associated with poor fetal
outcome. They indicate possible compromise if they become
prolonged or are persistent.
› most often seen during labour and in patients’ with reduced
amniotic fluid volume

28. › Variable decelerations can sometimes resolve if the mother
changes position
› Variable decelerations without the shoulders are more
worrying, as it suggests progressive hypoxia

30. › This type of pattern is rare, however, if present it
is very concerning.
› It is associated with high rates
of fetal morbidity and mortality.
Associated with
› Severe fetal hypoxia, severe fetal anaemia (Rh,TTT, BG),
fetal-maternal haemorrhage, butorphanol (opioid)
› Immediate C-section is indicated, outcome is usually poor.

32. › Reassuring
› Suspicious
› Abnormal
› The overall impression is determined by how many of the
CTG features were either reassuring, non-reassuring or
abnormal. The NICE guideline below demonstrates how
to decide which category a CTG falls into

33. › Baseline heart rate
› 110 to 160 bpm
› Baseline variability
› 5 to 25 bpm
› Decelerations
› None or early
› Variable decelerations with no concerning characteristics*
for less than 90 minutes

34. › Baseline heart rate
› 100-109 bpm or 161-180 bpm
› Baseline variability
› <5 for 30-50 min or >25 for 15-25 minutes
› Deceleration
› Variable decelerations
› Late decelerations with no maternal or fetal clinical risk
factors such as vaginal bleeding or significant meconium

35. › Baseline heart rate
› <100bpm >180 bpm
› Baseline variability
› <5 for more than 50 minutes or > 25 for more than 25 minutes
› Sinusoidal
› Decelerations
› Variable decelerations with any concerning characteristics or less if any
maternal or fetal clinical risk factors
› Late decelerations for 30 minutes (or less if any maternal or fetal clinical
risk factors)
› Acute bradycardia, or a single prolonged deceleration lasting 3 minutes or
more

36. › •High negative predictive value :>98% of fetuses with a
normal CTG will be OK.
› Poor positive predictive value :50% of fetuses with an
abnormal CTG will be hypoxic but 50% will be OK.
› A normal CTG is a good sign but a poor CTG does not
always suggest fetal distress.