Cardiotography CTG Flashcards
What is CTG used to measure?
- fetal heart rate
- contractions of uterus
- useful way of monitoring the condition of fetus and activity of labour
What does a CTG involve?
2 transducers are placed on the abdomen to get the CTG readout:
- one above the fetal heart to monitor the fetal heartbeat
- one near the fundus of the uterus to monitor the uterine contractions
Transducer above fetal heart monitors heartbeat using doppler US
Transducer near fundus uses US to assess tension in uterine wall, indicating uterine contraction
What are the indications for continuous CTG monitoring in labour?
- sepsis
- maternal tachycardia (>120)
- significant meconium
- pre-eclampsia (esp BP > 160/110)
- fresh antepartum hemorrhage
- delay in labour
- use of oxytocin
- disproportionate maternal pain
What are the key features to look for on a CTG?
- contractions - number of uterine contractions per 10 mins
- baseline rate - the baseline fetal heart rate
- variability - how fetal HR varies from baseline
- accelerations - periods where fetal HR spikes
- decelerations - periods where fetal HR drops
What do too many or too few contractions indicate on a CTG?
- too few indicate labour is not progressing
- too many can mean uterine hyperstimulation which can lead to fetal compromise
- also important to interpret fetal HR in context of the uterine contractions
What do accelerations indicate on a CTG?
-accelerations are generally a good sign that the fetus is healthy, esp when occuring alongside contractions of the uterus
What is a reassuring baseline rate and variability?
baseline rate - 110-160
variability - 5-25
What is a non-reassuring baseline rate and variability?
baseline rate of 100-109 or 161-180
varriabillity of <5 for 30-50 mins or >25 for 15 to 25 mins
What is an abnormal baseline rate and variability?
baseline rate of <100 or >180
varriabillity of <5 for over 50mins or >25 for over 25 mins
What do decelerations indicate on a CTG?
- more concerning finding where the fetal HR drops in response to hypoxia
- FH is slowing to conserve oxygen for vital organs
What are the 4 types of decelerations?
- early
- late
- variable
- prolonged
What are early decelerations and what are they caused by?
- are gradual dips and recoveries in HR that correspond with uterine contractions
- considered to be normal
- caused by the uterus compressing the head the fetus, stimulating the vagus nerve of the fetus, slowing the heart rate.
What are late decelerations and what are they caused by?
- gradual falls in HR that starts after the uterine contraction has already begun (delay between uterine contraction and deceleration)
- caused by hypoxia in the fetus and are a more concerning finding
- may be caused by excessive uterine contractions, maternal hypotension or maternal hypoxia
What are variable decelerations and what are they caused by?
- abrupt decelerations that may be unrelated to uterine contractions
- fall of >15 from baseline
- lowest point of deceleration occurs within 30 seconds and overall lasts <2 mins
- often indicate intermittent compression of the umbilical cord, causing fetal hypoxia
- Brief accelerations before and after the deceleration are known as shoulders, and are a reassuring sign that the fetus is coping
What are prolonged decelerations and what are they caused by?
- decelerations that last between 2-10 minutes with a drop of >15 from baseline
- often indicates compression of umbilical cord, causing fetal hypoxia
- are abnormal and concerning
