Cardiotography (Complete) Flashcards
(30 cards)
How does CTG work?
Records pressure changes in the uterus using internal or external pressure transducers to determine foetal HR
What acronym is used to interpret a CTG?
DR C BRAVADO
DR: Determine risk
C: Contractions
BRa: Baseline rate
V: Variability
A: Accelerations
D: Decelerations
O: Overal impression
Give examples of maternal factors which contribute to a high-risk pregnancy.
Gestational diabetes
Hypertension
Asthma
Smoking
Drug abuse
Absence of prenatal care
Give examples of obstetric factors which contribute to a high-risk pregnancy.
Multiple gestation
Post-date gestation
Previous cesarean section
Intrauterine growth restriction
Premature rupture of membranes
Congenital malformations
Oxytocin induction/augmentation of labour
Pre-eclampsia
How are contractions assessed on CTG?
Assess number and intensity
Number: Count number of contractions in 10 minute interval (10 big suqares)
Intensity: Determined by palpation of abdomen
e.g. 2 contractions in 10 minutes = “2 in 10”
What is the normal baseline foetal HR?
110-160bpm
Baseline determined by drawing line straight middle of accelerations/decelerations
What is considered bradycardia?
HR <110 bpm
In which cases is a baseline foetal HR of 100-120 considered normal?
Post-date gestation
Occiput posterior or transverse presentations
What are causes of baseline bradycardia?
Post-term gestation (100-120)
Occiput posterior and or transverse presentations (100-120)
Maternal use of beta-blockers
Foetal hypoxia (< 80 bpm for more than 3 minutes)
What bradycardic changes on CTG are indicative of severe neontal hypoxia?
Baseline < 80 bpm lasting longer than 3 minutes (3 boxes)
List examples of causes of prolonged severe bradycardia
Epidural and spinal anesthesia
Maternal seizures
Rapid foetal descent
Prolonged cord compression
Cord prolapse
Placental abruption
Uterine rupture
How is prolonged bradycardia managed?
If preceded by reduced variability or reduced variability within 3 minutes: Immediate delivery via quicket and safest route
If preceded by normal variability and cycling:
1) Rule out 3 serious causes
* Cord prolapse
* Placental abruption
* Uterine rupture
2) Check for non-serious underlying cause and manage
3) If not stabilised by 9 minutes: Immediate delivery via quickest and safest route
What is considered tacchycardia?
> 160bpm
What are causes of baseline tacchycardia?
Prematurity (HR should ideally be no less than <140 bpm)
Maternal pyrexia
Hyperthyroidism
Maternal or foetal anaemia
Chorioamnionitis
Hypoxia
What is the normal variability?
5-25
What are considered abnormal variabilities?
Less than 5 bpm > 50 minutes
More than 25 bpm for > 25 minutes
Sinusoidal variability
What is considered loss of baseline variations
Baseline variablity <5 bpm
What are causes of loss of baseline variation?
Foetal sleeping (most common and should last less than 40 minutes)
Prematurity (<28 weeks)
Foetal tacchycardia
Foetal hypoxia
Foetal acidosis
Drugs: opiates, benzodiazepines, methyldopa and magnesium sulphate
Congenital heart abnormalities
What is the most common cause of reduced baseline variability?
Foetal sleeping
Should be concerning if lasting >40 minutes
What aditional finding alongside loss of baseline variations is more indicative of foetal acidosis?
Late decelerations
List examples of drugs which can cause reduced baseline variability (4)
Opiates
Benzodiazepines
Magnesium sulphate
Methyldopa
What are acclerations?
Abrupt increase in the baseline fetal heart rate > 15 bpm for >15 seconds
What is the clinical significance of accelerations?
Reassuring especially if occuring alongside uterine contractions
What is early deceleration?
Decrease in HR following onset of contraction and returns to normal on completion of contraction
