This document discusses various abnormal fetal heart rate patterns seen on a cardiotocography (CTG) tracing during labor and delivery. It describes fetal tachycardia as a heart rate over 160 bpm and potential causes like infection or drugs. Fetal bradycardia below 120 bpm is ominous and can be caused by hypoxia. Early decelerations occur with contractions and recover after, while late decelerations begin with contractions but recover slowly, indicating hypoxia. Variable decelerations can be caused by cord compression. Reduced variability may indicate fetal sleep, acidosis, or drugs. Management depends on whether the CTG is reassuring or pathological, with pathological cases requiring specialist evaluation and potential urgent delivery.

1. ABNORMAL CTG
Rosshini Jagatheswaran

2. Foetal Tachycardia
Baseline heart rate >160 bpm
Causes:
 Chorioamnionitis – if maternal fever also present
 Thyrotoxicosis
 Increased foetal activity
 Drugs (tocolytic drugs, Vistaril, etc.)
 Foetal cardiac arryhthmias

4. Foetal Bradycardia
 indicates severe hypoxia
 Causes are:
 Prolonged cord compression
 Cord prolapse
 Epidural and spinal anaesthesia
 Maternal seizures
 Post-date gestation
 Occiput posterior or transverse
presentations
► <80bpm  OMNIOUS sign
Baseline heart rate < 120bpm
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6. Early Deceleration
 Physiological
 Starts when uterine contraction begins
 Recover when uterine contraction stops
 Periodic slowing of the fetal heartbeat, synchronized with the
contractions.
 Can be due to fetal head compression within the birth canal

8. Late Decelerations
 Begin at the beginning of uterine contraction
 Recover after the contraction ends
 Significantly non-reassuring
 Indicates there is insufficient blood flow through the
uterus & placenta, causing foetal hypoxia & acidosis.
 Fresh blood resupplies the intervillous space after the
contraction

10. Variable Deceleration
 Abrupt, visually apparent decreases in FHR below the
baseline FHR
 Start before, during or after uterine contraction starts
 Seen during labour and in patients with oligohydramnios
 Caused by umbilical cord compression
 Corrected by change in maternal position and
amniofusion

12. Prolonged Decelerations
 ≥15 bpm, lasting ≥2 minutes, but ≤10 minutes from
onset to return to baseline
 Causes:
 Maternal hypotension
 Cord prolapse
 Cord compression
 Maternal seizure

15. Reduced Variability
Caused by:
 Deep foetal sleep - this should last no longer than 40
minutes – most common cause
 Foetal acidosis (due to hypoxia)
 Foetal tachycardia
 Drugs – opiates, benzodiazipines, methyldopa,
magnesium sulphate
 Prematurity – variability is reduced at earlier gestation
(<28 weeks)

17. Normal variability Reduced variability

18. Sinusoidal Pattern
 It is described as:
 Smooth and regular
 Amplitude of between 5 -15 bpm around the baseline rate
 No beat to beat variability, accelerations

20. Management of Abnormal CTG
 District Hospital
Refer to hospital if CTG tracing non-reassuring and pathological. Reassure hydration,
patient in lateral position and oxygen
 Hospital with O&G Specialist
 Non-reassuring/Suspicious CTG –
Interpretation : Physiological or early chronic hypoxaemia
Action: Inform medical officer in-charge
 Abnormal/pathological CTG
Interpretation : Late chronic hypoxaemia or anaemia acute hypoxaemia (abruptio
placenta)
Action: Inform specialist in-charge. Prepare for urgent delivery