Foetal and maternal monitoring in labour

Question 1

What is a normal foetal HR on CTG?

Answer 1

-120-150bpm
-1 cm = 1min

Question 2

When is a foetal scalp electrode used instead of CTG?

Answer 2

-If there is poor contact with the abdominal transducer eg in cases of:
–High BMI
–Twins
–Abdominal scarring

Question 3

What key elements of the CTG are analysed during labour?

Answer 3

DR C BrAVADO
1. Determine Risk
2. Contractions (should be 4-5/10 min)
3. foetal Baseline Rate (120-150bpm)
4. Accelerations (rise of >15bpm for 15s)
5. Variability (5bpm or more)
6. Decelerations (drop of >15bpm for 15s)
7. Overall impression

Question 4

What features of contractions are monitored on a CTG?

Answer 4

-Frequency and duration
-NOT intensity (affected by size of mother - low BMI = greater intensity)

Question 5

What is a normal variability and what does low variability signify?

Answer 5

-Normal = 5-15bpm
-Low = sign of hypoxia
-High (>15) = acceleration (separate sign)

Question 6

Are accelerations good or bad?

Answer 6

-Presence = good - should have 2 accelerations in 20min
-Absence = not necessarily bad - baby might be asleep, occur in cycles

Question 7

What are decelerations a sign of?

Answer 7

Depends whether early or late in 2nd stage of labour:
-Early = deceleration matches contractions - head is getting squashed as it is pushed through the pelvis
-Late = normally a 15s time lag between contraction and deceleration
EARLY = not concerning
LATE = concerning

Question 8

What does the variability of a deceleration show?

Answer 8

-Variability = variability of foetal HR during acceleration
–Typical = <60s + <60bpm
–Atypical = >60s or >60bpm

Question 9

What is shouldering on a CTG?

Answer 9

-Brief acceleration on foetal trace after a deceleration
–Reassuring sign

Question 10

What are the pros and cons of CTG monitoring?

Answer 10

PROS
-Reduces rate of neonatal seizures
-Increases early intervention rate
CONS
-High false positive rate - more interventions
-Restricts maternal positioning

Question 11

What interventions can be done if a CTG is concerning?

Answer 11

-Change maternal positioning –> left lateral position improves placental blood flow
-Give fluids (?dehydration / exhaustion)
-Foetal scalp stimulation
-Foetal blood sample
-Delivery - instrumental or LCSC

Question 12

What does foetal scalp stimulation involve?

Answer 12

-Vaginal exam, foetus’s scalp is prodded
-If acceleration seen on CTG after stimulation –> reassuring

Question 13

How is a foetal blood sample taken?

Answer 13

NB cervix must be dilated to at least 3cm
-Amnioscope used to visualise baby’s head
-Capillary sample taken from scalp and measure foetal pH
->7.25 = normal
-7.20-25 = borderline, repeat in 30min
-<7.20 = deliver

Question 14

What difficulties arise when taking a foetal blood sample?

Answer 14

-Getting a clean sample is difficult
-Membranes must be ruptured
-Cervix must be 3cm dilated

Question 15

What observations are taken for maternal monitoring during labour?

Answer 15

-BP + HR
-Pain management
-4-hourly obstetric examination to determine:
–Cervical dilation
–Descent of the head
-Contractions (frequency, length and strength)
-Vaginal loss

Question 16

What are the different classifications of conclusions to be made from a CTG?

Answer 16

-Reassuring
-Suspicious (1 non-reassuring feature)
-Pathological (2 non-reassuring or 1 abnormal feature)
-Urgent intervention (acute bradycardia / prolonged deceleration for >3min)