CTG Monitoring Flashcards
What do the following abbreviations stand for in CTG monitoring?
DR C BRa V A D O
Define Risk Contractions Baseline Rate Variability Accelerations Decelerations Overall impression
What is define risk?
Defining whether a pregnancy is high or low risk. It gives you context to the CTG and may change your threshold for intervention
What do you need to record about contractions?
Number in a 10 minute period (seen as peaks of uterine activity on CTG)
Strength and duration
What is a normal fetal heart rate?
110-160
How is a baseline fetal heart rate calculated?
Average in 10 minute window
Ignore accelerations and decelerations
How is prolonged severe bradycardia in a fetus defined?
<80bpm for >3 mins
What conditions are associated with fetal tachycardia?
Fetal hypoxia
Chorioamnionitis
Maternal or fetal anaemia
Hyperthyroidism
What conditions are associated with fetal bradycardia?
Prolonged gestation
Transverse or posterior occiput presentation
(100-120 bpm)
What conditions are associated with prolonged severe fetal bradycardia?
Prolonged cord compression
Cord prolapse
Epidural
Rapid fetal descent
What does baseline variability on a CTG tell you? What is a normal variability?
How a fetus’ HR varies from one beat to the next
Indicate fetus is adapting to environment due to input from nervous system, baroreceptors and chemoreceptors
Normal is 5-25
What could cause reduced fetal variability?
Fetus sleeping Fetal acidosis - hypoxia Fetal tachycardia Congenital heart defect Prematurity Maternal medication - opiates, benzo, methyldopa, magnesium sulphate
What is a fetal acceleration?
Abrupt increase in baseline fetal HR
> 15bpm for >15s
They are reassuring
What is a fetal deceleration?
Abrupt decrease in baseline fetal HR of >15bpm for >15s
Why do foetuses reduce their heart rate?
In response to hypoxia to reduce myocardial demand and preserve myocardial oxygenation and perfusion
Fetus can’t change respiratory depth or rate
What is an early deceleration?
Start when uterus contract and recover when contraction stop
Due to fetal RICP and increasing vagal tone
Physiological deceleration
What is a variable deceleration?
Rapid fall in heart rate with variable recovery phase
May not have any relationship to contractions
Seen in labour and with oligohydramnios patients
What are “shoulders of decelerations”?
Accelerations occur before and after deceleration
Indicate fetus still able to adapt and not yet hypoxic
What causes the acceleration, deceleration, acceleration in shoulders of decelerations?
Umbilical vein occluded - acceleration
Umbilical artery occluded - deceleration
Pressure off cord - acceleration
What is a late deceleration?
Begin at peak of contraction and recover after it has ended
Indicate lack of blood supply to uterus and placenta - hypoxia and acidosis
What causes late decelerations?
Maternal hypotension
Pre-eclampsia
Uterine hyperstimulation
What must you do if you see a late deceleration?
Fetal blood sampling for pH
What is a prolonged deceleration?
Deceleration lasting >3mins
Fetal blood sampling or emergency C section needs to be arranged
What is a sinusoidal pattern on a CTG?
Smooth regular wave like pattern with no beat to beat variability
What can cause a sinusoidal CTG pattern?
Severe fetal hypoxia
Severe fetal anaemia
Haemorrhage
Very concerning and associated with high levels of morbidity and mortality
What would be seen on a reassuring CTG?
110-160bpm
5-25 variability
No or early decelerations
Variable decelerations with no concerning characteristics <90 mins
What characteristics of variable decelerations are concerning?
>60s Reduced baseline variability within deceleration Fail to return to baseline Biphasic (W) shape No Shouldering
What features of a CTG would be considered non-reassuring?
100-109bpm OR 160-181bpm
Variability <5 for 30-50mins or >25 for 15-25mins
Variable decelerations with no concerns >90mins
Variable decelerations with concerns in <50% of contractions >30mins
Variable decelerations with concerns in >50% of contractions <30mins
Late in >50% of contractions for <30 mins with no clinical risk factors (bleeding or meconium)
What features of a CTG would be considered abnormal?
<100 or >180 bpm
Variability <5 for >50 mins OR >25 for >25mins OR sinusoidal pattern
Variable decelerations with concerns >50% of contractions for >30 mins
Late decelerations >30mins
Acute bradycardia
Single prolonged deceleration >3mins
What is a normal CTG and what is the management?
All features reassuring
Continue CTG and usual care
What is a suspicious CTG and how is it managed?
1 non-reassuring AND 2 reassuring features
Seek advice from obstetrician or senior midwife, correct underlying causes, full set of maternal obs
What is a pathological CTG?
1 abnormal feature OR 2 non reassuring features
How is a pathological CTG managed?
Seek advice - obstetrician or senior midwife
Correct underlying cause
Exclude acute events - cord prolapse, placental abruption, uterine rupture
Offer digital fetal scalp stimulation
If still pathological after scalp stimulation, consider fetal blood sample and expediting birth
What CTG requires urgent intervention?
Acute bradycardia
Single prolonged deceleration >3mins
What is done if a CTG requires urgent intervention
Urgently seek obstetrician help Correct underlying causes Expedite birth if acute event Prepare for urgent birth Expedite birth if bradycardia >9mins Discuss expedited birth if bradycardia recover
What are the CI’s for fetal blood sampling?
Risk of maternal-fatal infection
Fetal bleeding disorders
What results are in a normal fetal blood sample? What is the next step?
Lactate <=4.1mmol/L
pH >= 7.25
Repeat in an hour
What results are in a Borderline fetal blood sample? What is the next step?
Lactate 4.2-4.8mmol/L
pH 7.21-7.24
Repeat in 30 mins
What results are in a Abnormal fetal blood sample? What is the next step?
Lactate >=4.9 mmol/L
pH <=7.20
Expedite birth
