CTG Flashcards
When is CTG used?
In antenatal high risk patients
What is described when looking at a CTG?
Patient ID. Date. Time. Paper speed. Contractions Baseline FHR Variability Accelerations Decelerations
Who are the high risk patients?
IUGR. Multiple pregnancies. Previous C/S. Oligohydramnios. Gestational DM. Induced labour. Prolonged ROM. APH. Pre-eclampsia. Post term pregnancies. Breech presentation. MSL. Premature babies.
What features of contractions should be seen on a normal CTG?
Duration
What feature of contractions is not evaluated on CTG?
Strength of contractions m
What are normal, non-reassuring and pathological features of the baseline FHR as seen on CTG?
Normal- 110-160
Non-reassuring- 100-109/ 161-180
Pathological- 180
What does the FHR respond to?
Any alteration in uteroplacental circulation, umbilical flow, fetal circulation and respiratory gas exchange
What is baseline variability and how is it measured?
= minor fluctuations in baseline FHR occurring at 3-5 cycles per minute
It is measured by estimating the difference in BPM between the highest peak and lowest trough in a 1 minute section
What is normal, non reassuring and pathological features of baseline variability as seen on CTG?
Normal- 5-25 BPM between contractions
Non reassuring- 90 minutes
What could cause reduced variability?
Sleep patterns
Fetal hypoxia
Maternal meds
Fetal abnormalities
Define a CTG acceleration
Brief increase in FHR of 15bpm or meow for 15 seconds or longer (periodic or episodic)
It is a reassuring sign
Define a deceleration
Brief episode of slowing of the FHR below the baseline by 15bpm or more lasting 15 seconds or more
What is the significance and implication of decelerations?
There are either non reassuring or abnormal
They indicate fetal hypoxia- uterine contractions cause decreased flow through the intervillus space –> fetus can become stressed due to diminished placental perfusion
What are the two types of non-reassuring decelerations?
Early
Variable
What causes early decelerations?
Vagal nerve stim due to head compression –> uniform, repetitive,boer iodide slowing down of the FHR early in the contraction and return to baseline at the end of the contraction
Typically occurs in sleep phase
Often seen between 4-8cm dilatation
What is a variable deceleration?
Variable, intermittent, periodic slowing of the FHR with rapid onset and recovery
May occur in isolation but commonly with contractions
Acel before and after variable decelerations = shouldering = sign of well oxygenated fetus
Due to umbilical cord compression- occlusion of umbilical vein –> decreased venous return –> reflex tachycardia to maintain cardiac output
What are the four types of pathological decelerations?
Late
Atypical variable
Spontaneous
Prolonged
What is a late (type 2) deceleration?
Repetitive periodic slowing of FHR with onset in middle/end of contraction and ending well after end contraction
Caused by decreased placental blood flow –> Too much lactic acid in fetus after contraction- may indicate fetal hypoxia/ asphyxia
Can cause increased variability or an increase in FHR
The smaller the baby, the lesser the reserve to cope
What is an atypical variable deceleration?
FHR slow to return to baseline after end of contraction (May last for >60 seconds)
Caused by uteroplacental insufficiency- more associated with fetal hypoxia and low Apgar scores
Seen with a loss of variability, loss of shouldering, delayed recovery to baseline or continuation of baseline rate of lower level or with the W signs (biphasic)
What is a spontaneous deceleration?
Occurs without any contractions
Fetal decompression at rest
First sign of abruptio or end stage of placental dysfunction
What is a prolonged deceleration?
Abrupt decrease in FHR level below the baseline lasting 60-90 seconds sometimes crossing 2 contractions (>3 min)
Occurs when the cause of deceleration is not reversed- prolonged head compression, cord compression, tetanic uterine contractions
What are the three categories of CTGs?
Normal
Suspicious (abnormal pattern requiring further assistance)
Pathological (abnormal pattern requiring immediate delivery)
How is are the CTG categories assessed?
Reassuring/ normal - all features reassuring
Suspicious- 1 non-reassuring feature present
Pathological- 2 or more non-reassuring features present OR 1 or more abnormal features present
How do you manage a patient with an abnormal CTG?
Intrauterine resus-
Call someone. Change position to relieve cord pressure (–> LL position). Stop oxytocin if being induced. Tocolyse with IV salbutamol. Increases IV fluids to increase circulating volume and placental perfusion. Perform fetal blood sampling/ blood gas. Give O2 to maximize fetal oxygenation.
What is a CTG?
It is a graphical record of the fetal heart rate pattern and contraction pattern
