08 ctg isam ws
TRANSCRIPT
Fetal cardiotocography CTG
Dr Isameldin Elamin MD DOWH MBBS
Assistant Professor
Obstetrics & Gynaecology
By the end of this lectures Student should be able: To recognize different part of CTG. To describe how CTG works. To discuss the maternal risks which need
electronic fetal monitoring. To read and interpret the CTG.
Objectives
Cardiotocography (CTG) is a technical means of recording (-graphy) the fetal heartbeat (cardio-) and the uterine contractions (-toco-) during pregnancy.
The machine used to perform the monitoring is called a Cardiotocograph, more commonly known as an Electronic Fetal Monitor (EFM).
Introduction
Changes in FH rate patterns occur in
response to changes in O2, CO2, hydrogen
ions and arterial pressure
These changes are mediated via the vagus
nerve, chemoreceptors & carotid body
baroreceptors
Pathophysiology of FH rate changes
It is difficult to measure fetal oxygenation and
pH continuously
FH rate patterns only allow indirect
assessment of fetal acid-base balance.
Fetal scalp sampling is required to confirm
whether the fetus is hypoxic…
Pathophysiology of FH rate changes
The heart rate of the fetus is calculated
using a Doppler ultrasound transducer.
signals detected are cardiac movement.
what is actually measured is the time
interval between cardiac cycles. this is converted
to heart rate.
Principle of CTG
CTG monitors: Fetal heart rate (FHR). uterine contractions.
prints on a two-channel strip chart recorder.
Principle of CTG…CONT.
CTG obtained by:
external transducers that are placed on the
maternal abdomen.
Internal monitoring by:
spiral electrode onto the fetal scalp.
plastic catheter
transcervically to monitor uterine contractions.
Principle of CTG…CONT.
2 electrode one for FHROne for uterine contraction
for FHR on lower abdomenfor uterine contraction on upper abdomen
CTG machine and paper
CTG probes Feto and toco
Setting CTG machine speed 1cm or 2 or 3 cm per minute
Internal monitoring
CTG trace showing Uterine contraction and fetal heart rate
Perinatal outcomes
50% reduction in neonatal seizures … but no difference in incidence of: - long-term neurological handicap - or perinatal mortality.Obstetric outcomes
66% increase in Caesarean section rate16% increase in instrumental delivery
CTG: Aim & out comes
CTG Should be reserved for high risk pregnancies.
(CTG) is the accepted standard for: intra-partum fetal monitoring in women with
additional risk factors.
Non-sterss test (NST) for fetal monitoring in
women not in labour.
CTG: Aim & out comes
Fetal risks:Intrauterine growth restrictionOligohydramniosAbnormal Doppler velocimetryPreterm labourMultiple pregnancyBreech presentationRhesus iso-immunisation
Risk factors
Maternal risks: Previous Caesarean section Pre-eclampsia Pregnancy >42 weeks Prolonged ROM >24 hours Diabetes Antepartum haemorrhage Significant medical condition – eg cardiac
Risk factors CONT.
Meconium stained liquor. Abnormal FHR on auscultation
Tachycardia Decelerations.
Maternal pyrexia 38°C once or 37.5°C on 2 occasions 2 hours apart
Fresh bleeding in labour Oxytocin augmentation
Changing from low risk to high risk
Many school for interpretation of CTG NICE, ACOG, ALSO, others All Through the following features: Basal heart rate (BHR). Beat to beat variability. Accelerations. Decelerations. Uterine contractions.
CTG reading and interpretation
Letters to make reading CTG more easy.
Determine Risk Assess degree of “clinical risk” in relation to perinatal
outcomes
Low
Medium
High
DRCBRAVADO
Uterine Contraction
BASE LINE HEART RATE
ACCELERATIONS
VARIABILITY
DECELERATIONS
OVER ALL ASSESSMENT
DRCBRAVADO….cont.
Baseline Fetal Heart Rate
Must be >15 bpm and >15 sec above baseline Should be >2 per 15 min period Always reassuring when present May not occur when fetus is “sleeping” Should occur in response to fetal movements or
fetal stimulation Non reactive periods usually do not exceed 45
min (>90 min and no accelerations is worrying)
Accelerations
Accelerations
It is the most important feature of any CTG
Is a reflection of competing acceleratory and
decelerating CNS influences on the fetal heart
And therefore represents the best measure of
CNS oxygenation, so its absent may indicate CNS
hypoxia
Variability
Absent – undetectable Minimal less than or equal to 5bpm Moderate 6 to 25 bpm Marked greater than 25 bpm Will be affected by drugs and fetal sleeping
cycles Will be reduced in the pre term fetus and
congenital heart abnormalities
Variability…CONT.
variability
Reduced Normal
Variability
Early: mirrors the contractionTypically occurs as the head enters the
pelvis and is compressed, i.e. it is a vagal response
Late: Follows every contraction and exhibits a slow return to baseline
Uncommon, the response of a hypoxic myocardium
Uteroplacental insufficiency
Decelerations
Variable: Show no relationship to contractions
Variable shape, onset and durationUmbilical cord compression
In practice many decelerations are MIXED
CONT..
Early deceleration
Early Deceleration
Associated with fetal compromise (hypoxia) but only in 50-60% of cases
Ominous if associated with:- fresh particulate meconium- ‘high-risk’ clinical situation
Ominous if:- ‘lag-time’ (peak to trough)- deceleration is slow to recoverBeware of SHALLOW, DELAYED decelerations
Late Decelerations
Late Decelerations
Late Decelerations
• Begin after onset of contraction
• Nadir (or trough) after peak of contraction
• Return to baseline after end of contraction
Late Decelerations
Early vs. late decelerations
Most decelerations in labour are variableCan reflect cord compression‘Variable’ in shape, depth and/or onsetUsually benign but …. if late or deep may
imply cord prolapsed or hypoxia ‘Shoulders’ before and/or after ( )
are amore benign featureNeed to assess the frequency and duration
Variable Decelerations
Variable decelerations
Variable decelerations
Smooth undulating, sine wave pattern Defined by an amplitude of 10bpm in cycle of two
to five per minute, lasting at least two minutes. May be a terminal pattern -severe hypoxia Associated with severe fetal anaemia, hydrops
and fetomaternal haemorrhage. False sinusoidal pattern not uncommon,
particularly if intermittent and with normal variability
In a true sinusoidal pattern variability is absent
Sinusoidal pattern
Sinusoidal pattern
Sinusoidal pattern
Prolonged deceleration
CTG- Twins
CTG- Late deceleration+ decreased variabilityexample:
Frequency = no. in 10 minutesDuration of each contractionInterval = between end of one and starting of the next contractionMore than 5/10 min= tachysystoleIntensity- can not be directly measured by external CTG
Uterine contractions
Cord compression=variable deceleration. Head compression=early deceleration. Placental insufficiency= late deceleration
Remember
CTG Interpretation
No decision on the basis of (CTG) findings alone.
Take into account: risk factors. woman. unborn baby progress of labour.
Overall care
Care remains on the woman rather than the CTG trace.
Remain with the woman at all times.
Assessment of woman and baby hourly, or more
frequently if there are concerns.
Assess and document all 4 features. Not possible to categorise every CTG trace. Accelerations is a sign that the baby is healthy. If fetal blood sample cannot be obtained, but
results in accelerations, decide according to clinical circumstances and in discussion with the woman.
Principles for CTG interpretation
Baseline FHR (beats/ minute). Baseline variability (beats/ minute). Decelerations. Acceleration
CTG Features
Normal/ reassuring. Non-reassuring. Abnormal.
Description of Features
CTG is normal/reassuring. healthy fetus CTG is non-reassuring. increased risk of fetal acidosis Suggest conservative measures.
CTG Categories
CTG is abnormal more likely associated with fetal acidosis
indicate conservative measures Further testing. CTG is abnormal needs urgent intervention. very likely to be associated with current
fetal acidosis
100-160
normal/reassuring.
161–180 Non-
reassuring.
Above 180 or below 100. Abnormal.
Baseline FHR (beats/ minute)
5 or more. normal/reassuring.
less than 5 for 30–90 minutes. Non-
reassuring.
Less than 5 for over 90 minutes. Abnormal.
Baseline variability (beats/minute).
Normal/reassuring. None or early deceleration.
Decelerations
Non-reassuring:
Variable decelerations:
dropping = < 60 beats for 60 seconds or
less.
over 90 minutes
over 50% of contractions
deceleration
Variable decelerations:
more than 60 beats
or taking over 60 seconds.
present for up to 30 minutes
over 50% of contractions
Or Late decelerations: present for up to 30 minutes occurring with over 50% of contractions
Abnormal deceleration: Non-reassuring variable decelerations after conservative measures for 30 minutes. with over 50% of contractions.
Late decelerations for over 30 minutes not improve with conservative measures. with over 50% of contractions.
Bradycardia or a single prolonged deceleration lasting 3 minutes or more
CTG is normal/reassuring: All 3 features are normal/reassuring.
CTG is non-reassuring and suggest need conservative measures:
1 non-reassuring+2 normal/reassuring features
Interpretation of CTG or CTG categories
CTG is abnormal and indicate need for
conservative measures and further testing
1 abnormal Feature
OR 2 non-reassuring features
CTG is abnormal and indicate needs for urgent
intervention:
Bradycardia.
a single prolonged deceleration with
baseline below 100 beats/minute, persisting
for 3 minutes or more
Continue CTG and normal care.
remove CTG after 20 minutes if normal and
no risk factors
If CTG is normal/reassuring:
If fetal heart rate is over 160 beats/minute check temperature and pulse give fluids and paracetamol.
Start 1 or more conservative measures: mobilise and left-lateral position intravenous fluids stopping oxytocin offering tocolysis.Inform midwife and obstetrician.
CTG is non-reassuring
If fetal heart rate is over 180 beats/minute check temperature and pulse give fluids and paracetamol.
Start 1 or more conservative measures: mobilise left-lateral position intravenous fluids stopping oxytocin offering tocolysis. Inform midwife and obstetrician
CTG is abnormal + conservative measures +testing
Offer FBS after conservative measures. expedite birth if: FBS cannot be obtained no accelerations. Take action sooner than 30 minutes if: late decelerations + tachycardia +reduced
variability. Inform and discuss with the consultant if: FBS result is abnormal. FBS cannot be obtained third FBS is thought to be needed.
Start conservative measures. Inform midwife and obstetrician Urgently seek obstetric help Make preparations for urgent birth Expedite birth if persists for 9 minutes If heart rate recovers before 9 minutes, reassess
decision to expedite birth in discussion with the woman.
CTG is abnormal + urgent intervention
Classification of fetal blood sample results
Normal: offer repeat after 1 hour. Or sooner if additional non-reassuring or
abnormal features are seen. Borderline: offer repeat sampling in 30 minutes. Or sooner if additional non-reassuring or
abnormal features are seen.
Discuss with the consultant obstetrician if: a fetal blood sample cannot be obtained or a third fetal blood sample is thought to be
needed.
Description FHR variability Decelerations
Normal/reassuring 100–160 5 or more None or early
Nonreassuring 161–180 less than 5for 30–90 minutes
Variable decelaration:drop=<60 beats recover=<60 seconds for 90 minutes.Drop>60 beats recover>60 seconds up to 30 minutes.Late decelerations: present for up to 30 minutes
Abnormal Above 180orbelow 100
Less than 5for > 90 minutes
Still Non-reassuring for 30 minutes after conservative.Late decelerations >30 minutesnot improve with conservative.Bradycardia or deceleration =>3 minutes.
Conclusion CTG features
CTG Category Definition Interpretation Managementnormal/reassuring 3 features are
normal/reassuringHealthy fetus Remove CTG after 20
minutesNon-reassuring 1 non-reassuring
feature risk of fetal acidosis conservative measures
Abnormal : need for conservative measures AND further testing
1 abnormalOR2 non-reassuringfeatures
fetal acidosis more likely
conservative measuresFBS
Abnormal: need for urgent intervention
Bradycardiasingle prolonged deceleration for 3 minutes
current fetal acidosis
conservative measuresmake preparations for urgent birth
Conclusion CTG trace interpretation
Variable deceleration decreased variabilityCTG categary:Abnormal : need for conservative measures AND further testing FBS needed
BradycardiaCTG is abnormal and indicate needs for urgent intervention
Normal CTG with acceleration
variable decelerations with the V-shaped picture are a normal, reflex response to umbilical cord compression.
A preeclamptic patient at 33 weeks gestation with IUGR is undergoing induction of labor. The fetal heart rate tracing shows evidence of uteroplacental insufficiency and is nonreassuring.
A 23-year-old G1P0 at 42 weeks is undergoing induction of labor. She is receiving intravenous oxytocin. She complains that her contractions are very painful and seem to be continuous.
A patient at 41 weeks is undergoing NST. Her NST is reassuring.
Interpretations of CTG in uptodate: Category1=normal CTG Category2=nonreassuring. Category3=abnormal.
Uptodate and ACOG
intrapartum care: nice guideline cg190 (december 2014)
essentials of obstetrics & gynaecology hacker & moore, fifth edition
obstetrics by ten teachers 19 editions. http://www.uptodate.com.
Further reading
THANK YOU