Cardiotocography

Question 1

Variability

Answer 1

• Result of integrated activity between sympathetic + parasympathetic branches of ANS
• Normal 5-10 (25?)
• Absence of variability:
  —> Poor predictor of hypoxic injury + metabolic acidosis
  —> Associated conditions: Fetal sleep cycle, prematurity, fetal hypoxia, fetal arrhythmia, congenital CVS / CNS anomalies / drug-induced sedatives / anaesthetics

Question 2

Acceleration

Answer 2

• Abrupt increase in baseline fetal HR >15bpm for >15s
• Associated with fatal movement
• Absence of acceleration:
  —> Poor predictor of hypoxic injury + metabolic acidosis
  —> Associated conditions: Fetal sleep cycle, prematurity, fetal hypoxia, fetal arrhythmia, fetal anaemia, congenital CVS / CNS anomalies

Question 3

Deceleration

Answer 3

• Abrupt decrease in baseline fetal HR >15bpm for >15s

Types:
1. Early
- uniform in shape + occur with each contraction (mirror image —> HR reaches lowest point at peak of contraction)
- recovered to baseline by end of contraction

2. Late
   - uniform in shape + depth
   - occur after each contraction with lowest point occur >15s after peak of contraction
   Causes:
   - **Excessive uterine contractions (Tachysystole)
   - **Maternal hypotension
   - ***Maternal hypoxaemia
   - Reduced placental exchange: Hypertensive disorders, DM, IUGR, Abruption
3. Variable (most common)
   - inconsistent in shape and frequency
   - Typical: “shoulders”, acceleration on either side of deceleration, could be ***physiological response to cord compression
   - Atypical: loss of shouldering, delayed recovery of FHR, rebound tachycardia, reduction in variability during deceleration, biphasic deceleration
4. Prolonged
5. Sinusoidal

Question 4

Cardiotocography results

Answer 4

Interpretation:
***DR. C BraVADO
- DR: Define risk (e.g. co-existing IUGR)
- C: Contraction
- Bra: Baseline rate
- V: Variability
- A: Acceleration
- D: Deceleration
- O: Overall impression

1. Reassuring
   - Baseline HR: 110-160
   - Baseline variability: 5-25
   - Deceleration: None / Early, Variable deceleration with no concerning characteristics for <90 mins
2. Non-reassuring
3. Abnormal
   - Require delivery / further action

Question 5

SpC OG: Time for implementation of CTG vs Tocography

Answer 5

CTG: >=28 weeks (machine cannot pick up fetal heart earlier than that)
Tocography: >=24 week