interpreting CTG Flashcards
what is the acronym for CTG?
DR: Define risk C: Contractions BRa: Baseline rate V: Variability A: Accelerations D: Decelerations O: Overall impression
what are maternal factors that make a CTG high risk?
Gestational diabetes
Hypertension
Asthma
what are obstetric complications of that make a CTG high risk?
Multiple gestation Post-date gestation Previous cesarean section Intrauterine growth restriction Premature rupture of membranes Congenital malformations Oxytocin induction/augmentation of labour Pre-eclampsia
what is the base rate for fetal heart rate?
110-160 bpm
what is considered fetal tachycardia?
baseline heart rate >160
what are causes of fetal tachycardia?
- fetal hypoxia
- chorioamnionitis
- hyperthyroidism
- fetal or maternal anaemia
- fetal tachyarrhythmia
what is defined as fetal bradycardia?
- baseline heart rate of <100
which situations is it common to have baseline HR between 100-120 bpm?
- post-date gestation
- occiput posterior or transverse position
what values would be seen for severe bradycardia on CTG?
- 80bpm >3minutes
what are causes of prolonged severe bradycardia?
- prolonged cord compression
- cord prolapse
- epidural and spinal anasthaesia
- maternal seizures
- rapid fetal descent
what is reassuring baseline variability?
5-25 bpm
what is non reassuring baseline variability?
<5bpm for 30-50 mins
>25bpm for 15-25 minutes
what is abnormal variability?
<5bpm >50 mins
>25bpm >25 mins
sinusoidal
what is the most common cause of reduced variability in the CTG?
fetal sleeping-> no longer than 40 mins
what are worrying causes of reduced CTG variability?
- fetal acidosis due to hypoxia
- drugs: benzodiazepines, methyldopa and magnesium sulphate
- prematurity- variability is reduced at low gestational ages <28 weeks
- congenital heart abnormalities