1.8 - CTG INCOMPLETE - (HR)

Question 1

What would be considered a normal foetal heart rate?

Answer 1

110-160

Question 2

When can a CTG reliably be performed?

Answer 2

Third trimester => After 28 weeks

Question 3

What rate of contractions would be concerning?

Answer 3

5 in 10 or 7 in 15 would be concerning for uterine hyperstimulation => Uterine rupture

Question 4

What are all the parameters to check for in CTG. What i mean by that is include the normal ranges where applicable

Answer 4

Define Risk: High vs low (continuous monitoring only for high risk)

Contractions: #/10 minutes or /15 mins
Baseline foetal heart Rate: 110-160
Variability: 5-25 bpm/beat
Accelerations: 2 in 20 is reassuring

Question 5

In what patients should CTG be performed?
Give 8 reasons

Answer 5

Any patient with high risk =>
Maternal Factors:
1) GDM
2) HTN/Pre-eclampsia/Eclampsia
3) Asthmatics

Obstetric Factors:
1) Multiple Gestation
2) Post-term
3) PROM/Pre-term delivery
4) IUGR
5) Placenta Previa
6) APH
7) Foetal anomalies
8) Induction

Environmental:
1) Smoking
2) Drug abuse

Question 6

What is recorded on a CTG paper?

Answer 6

Maternal details
Date and time
Maternal posture (why? early Decelerations)
Speed of paper
drugs administered esp. Epidural and induction
Vaginal examinations

Question 7

How does the foetal heart rate respond to Acute hypoxia
Chronic Hypoxia

Answer 7

Acute = increased PNS => bradycardia
Chronic = chronic increase in SNS => tachycardia

Question 8

How does the foetal heart rate respond to
Hypertension
Hypotension

Answer 8

Hypertension: increased PNS => bradycardia
Hypotension: Increased SNS => Tachycardia

Question 9

Give 4 causes of Persistent foetal tachycardia and 4 causes of persistent foetal bradycardia

Answer 9

Persistent Tachycardia
Chronic Hypoxia
GA<32
Infectious: Maternal pyrexia, foetal infection, chorioamnionitis
Hyperthyroidism
Catecholamines

Persistent Bradycardia:
Post-term
Cord compression
Cord prolapse
Congenital heart disease/heart block
Maternal seizure
Maternal benzos

Question 10

Why would GA<32 cause persistent bradycardia?

Answer 10

Vagal immaturity (vagus in charge of PNS + unopposed SNS)

Same thing for post-dates causing persistent bradycardia as there is increased vagal tone => more PNS

Question 11

Define reduced variability
Give 3 causes for reduced variability

Answer 11

Reduced variability is variability <5 for >40 minutes (>90 if pathological)

1) Foetal sleep (should not last for more than 40 minutes anyways)
2) Analgesia: Epidural and Opioids
3) Induction agents: Oxytocin and prostaglandin
4) Betamethasone (steroid given. Thats why we give dexamethasone instead)

Question 12

What is a sinusoidal pattern?
Give 2 causes

Answer 12

Smooth, undulating sinusoidal wave-like pattern with no beat to beat variability.

Causes
Idiopathic
Anaemia due to Rhesus isoimmunization (haemolytic anaemia), or large APH
Severe hypoxia

Question 13

Accelerations occur as a response to fetal movements or to uterine contractions. Define Accelerations

Answer 13

Abrupt increase of 15bpm for >15s
(decelerations is the opposite)

Question 14

Define reactive accelerations

Answer 14

reduced bp followed by an abrupt increase of 15bpm for >15s

Question 15

Decelerations are an abrupt decrease of 15bpm for >15 seconds. Define early deceleration.

Give 2 causes of early decelerations

Answer 15

Begins at the onset of a contraction and recovers by the end of it with the lowest point preceding contraction peak

Compression of the fetal head during contraction (=> increased ICP => increased vagal tone => reduced HR)
or Change in maternal posture (thats why we record it)

Question 16

Accelerations often proceed after variable decelerations. Define variable decelerations

Give the etiology and 2 causes of variable decelerations

Answer 16

Decelerations (abrupt decrease by 15bpm lasting >15s) that is inconsistent with contractions

It indicates a transient compression of the umbilical cord not related to contractions
=> Nuchal cord, Cord prolapse

Question 17

Define late decelerations
Give the etiology and 5 reasons for its occurance

Answer 17

Decelerations (abrupt decrease by 15bpm lasting >15s) that occur after the onset of contraction and the lowest point being 15s after peak of contraction

This is typically caused by Faetal acidosis from:
Acutely:
Maternal hypotension
Placental abruption
Antepartum hemorrhage
Rhesus isoimmunisation

Chronic:
GDM
Hypertension/PET
Renal disease
TTTS

Question 18

Prolonged decelerations are often preceded by variable decelerations. Define Prolonged deceleration
Give 3 causes

Answer 18

Drop in FHR of >30bpm for >2 minutes

Cord prolapse/total cord occlusion
Uterine hyperstimulation
After AROM or vaginal exam

Question 19

you notice this CTG. What is it demonstrating and what is your management plan?

Answer 19

Terminal bradycardia
Emergency C section or immediate operative delivery if enough descent.