CTG Flashcards
Define a normal CTG
Baseline FHR 110-160 bpm
Normal baseline variability 6-25 beats
Accelerations 15 beats above baseline lasting 15sec
No decelerations
Define the different levels of variability and what variability is a sign of
6-25 normal
3-5 reduced
25 increased
Normal baseline variability is a sigh of adequate fetal O2
What does increased variability indicate
Reflects exaggerated response to acute hypoxia as the fetus tries to recover “saltatory pattern”. Most commonly - Hyperstimulation in between contractions, following a prolonged deceleration.
Define an abnormal CTG
Baselin FHR 160bpm. baseline variability 25. Accelerations absent. Deceleration: early, late, variable.
Cause of bradycardia on CTG
Drugs e.g. local anaesthetic, b blockers
Maternal - Hypothermia, hypoglycaemia, hypotension, hyper contractility.
Fetal - Heart block, cord compression, cord prolapse, low inherent rate.
Cause of Tachycardia on CTG
High inherent
Maternal - Fever, hyperthroidism, anaemia
Fetal - arrhythmia, anaemia
Drugs - Sympathomimetics
Uteroplacental - early hypoxia (abruption, HTN), Chorioamnionitis.
Causes of decreased variability
Maternal - infection, dehydration
Fetal - CNS anomalies, dysrhythmia, inactivity/sleep cycles, preterm fetus.
Drugs - Narcotics, sedative, MgSO4, B blocker.
Uteroplacental - hypoxia
When to do fetal scalp blood sampling
when atypical or abn FHR is suggestive by clinical parameters e.g. heavy meconium or moderately to severely abn FHR, low variability, repetitive late deceleration, complex variable deceleration or cardiac arrhythmias.
Results: PH greater 7.25 normal
pH 7.21-7.24 repeat in 30min or delivery if rapid fall
pH less then 7.20 indicated fetal acidosis which needs delivery.
Contraindicated in fetal blood dyscrasia or active maternal infection.
Types of Decelerations
Early deceleration - benign due to vagal response to head compression.
Variable deceleration - due to cord compression or 2rd stage contraction. Concerning if decel below 60 HR or drop by more then 60 beats below baseline and greater then 60s to return to baseline.
Complicated variable deceleration - to less then 70bpm, for greater then 60s, loss of variability or decrease in baseline after deceleration, Biphasic deceleration, slow return to baseline, baseline tachycardia or bradycardia.
Late decelerations- peak of deceleration after peak of contraction, slow to return to baseline, may cause decreased variability and change in baseline, due to fatal hypoxia, academia, maternal hypotension or uterine hypertonus, usually a sign of uteroplacental insufficiency.
Mx of abnormal FHR
POSION - ER Position (LLPD) O2 IV fluids - correct hypotension Fetal scalp stimulation Fetal scalp electrode Fetal scalp pH Stop Oxytocin Notify MD Vaginal Exam to rule out cord prolapse Rule out fever, dehydration, drug effects, prematurity If fail then C/S
Define Atypical tracing (Category 2)
Baseline- bradycardia (100-110) Tachycardia (more then 160 for 30-80min), Rising baseline.
Variability - less then 5bpm for 40-80min
Deceleration - Repetitive more then 3 uncomplicated, variable decelerations, occasional late deceleration, any prolonged deceleration 2-3min.
Acceleration - absent with scalp stimulation
Action – further assessment required.
Define abnormal tracing (Category 3)
Baseline bradycardia less then 100 or tachycardia greater then 160 for greater then 80min. or erratic baseline
Variability- less then 5 bpm for 80min or greater then 25 for 10min
Deceleration - Repetitive complicated variable decelerations, repetitive late decelerations, any prolonged deceleration greater then 3min.
Acceleration: nearly absent
Action: Scalp pH, prepare and possible delivery.
Sinusoidal pattern
An oscillating pattern resembling a sine wave (very smooth and very regular)
Absent BL variability or accelerations
A relatively fixed period of 2-5 cycles per minute
An amplitude of 5-15 beats
Usually indicative of severe fetal anaemia (Hb < 5g/dl)
