WK5: fetal surveillance

Question 1

Define IA

Answer 1

the auscultation of the fetal heart using a hand-held Doppler at regular intervals and for a pre-defined duration during labour.

Question 2

How frequently should IA be completed in lanour?

Answer 2

• Every 15-30 minutes in the active phase of the first stage of labour
• With each contraction or at least every five minutes in the active second stage of labour.

Question 3

What are some key practice point of IA in labour?

Answer 3

• Each auscultation episode should commence toward the end of a contraction and be continued for at least 30-60 seconds after the contraction has finished. (document resting fetal health when out of contraction)

Auscultation in labour should be undertaken and documented:
First stage: Every 15-30 minutes in the active phase of the first stage of labour.
Active second stage: With each contraction or at least every five minutes

Question 4

What is the normal baseline range for fetal heart rate? and what may change this and when should it be assessed?

Answer 4

Baseline= 110-150 BPM
Younger gestational age will sit higher than older fetus’

Assessed in the absence of
- fetal movements
- uterine activity
- and decelerations

Question 5

What is normal, increased, reduced and absent variability?

Answer 5

Absent: <3 BPM
Reduced: 3-5 BPM
Normal: 6-25 BPM
Increased >26 BPM

Question 6

Define an acceleration

Answer 6

The increase from the baseline of 15 BPM for 15 seconds.

Transient increases in FHR of 15 bpm or more above the baseline and lasting 15 seconds
at the baseline. Accelerations in the preterm fetus may be of lesser amplitude and shorter
duration. The significance of no accelerations on an otherwise normal CTG is unclear.

Question 7

What is considered a decel?

Answer 7

a drop in FHR for >/15 secs

Transient decreases of the FHR below the baseline lasting at least 15 seconds, conforming
to one of the patterns e.g. early, later, variable, complicated variable, prolonged, bradycardia.

Question 8

What are some abnormalities that when they occur alone or unlikely to relate to fetal compromise?

Answer 8

• Baseline rate 100-109 bpm.
• Reduced or reducing baseline variability 3-5bpm.
• Absence of accelerations.
• Early decelerations.
• Variable decelerations without complicating features.

Question 9

What are some features that are associated with fetal compromise and demand action?

Answer 9

• Baseline fetal tachycardia >160 bpm.
• Rising baseline fetal heart rate (including where it remains within normal range).
• Complicated variable decelerations.
• Late decelerations.
• Prolonged decelerations (a fall in the baseline fetal heart rate for more than 90 seconds and up to 5 minutes).
  MORE URGENT ATTENTION=
• Bradycardia (a fall in the baseline fetal heart rate for more than 5 minutes).
• Absent baseline variability <3bpm.
• Sinusoidal pattern.
• Complicated variable decelerations with reduced or absent baseline
  variability.
• Late decelerations with reduced or absent baseline variability.

Question 10

Define tachysystole

Answer 10

= more than five active labour contractions in ten minutes, without fetal heart rate abnormalities.

Question 11

Define uterine hypertonus

Answer 11

= contractions lasting longer than two minutes in duration or contractions occurring within 60 seconds of each other, without fetal heart rate abnormalities.

Question 12

Define uterine hyperstimulation

Answer 12

Excessive uterine activity, (either tachysystole or uterine hypertonus) WITH fetal heart rate abnormalities.

Question 13

What is the appropriate management for tachysystole and hypertonus?

Answer 13

• continuous cardiotocography;
• consideration of reducing or ceasing oxytocin infusion;
• maternity staff remaining with the woman until normal uterine activity is observed; and
• consideration of tocolysis
• reposition mother
• VE to see if fully dilated and can push

Question 14

What is the appropriate management for uterine hyperstimulation?

Answer 14

• continuous cardiotocography;
• reducing or ceasing oxytocin infusion;
• maternity staff remaining with the woman until normal
  uterine activity is observed;
• consideration of tocolysis; and
• consideration of urgent delivery
• Excessive uterine activity in the absence of evidence of fetal
  compromise is not in itself an indication for tocolysis.

Question 15

Define sinusoidal

Answer 15

A regular oscillation of the baseline FHR resembling a sine wave.
- absent baseline variability or accelerations
- a relatively fixed rate of 2‐5 cycles per minute
- typically, an amplitude of 5‐15 beats
- reduced fetal movements is a key clinical feature
- is usually indicative of severe fetal anaemia (Hb < 50g/L)
- may not start out as an overt sinusoidal pattern!
- there is nothing normal about a true sinusoidal pattern!

This smooth, undulating pattern is persistent, has a relatively fixed period of 2 –5 cycles per minute and an amplitude of 5 –15 bpm above and below the baseline. Baseline variability is absent and
there are no accelerations.

Question 16

Define baseline fetal heart

Answer 16

The mean level of the fetal heart rate when this is stable, excluding accelerations and
decelerations and contractions. It is typically determined over a time period of 5 or 10
minutes and expressed in bpm. Preterm fetuses tend to have values towards the upper end
of this range. A progressive rise in the baseline is important as well as the absolute values.

Question 17

Define an early decel

Answer 17

Uniform, repetitive decrease of FHR with slow onset early in the contraction and slow return
to baseline by the end of the contraction.
- uniform in shape
- typically seen in sleep

Are benign

Question 18

Define variable decels

Answer 18

Repetitive or intermittent decreasing of FHR with rapid onset and recovery. Time relationships with contraction cycle may be variable but most commonly occur simultaneously with contractions

Cause: cord compression
- variable in time, duration and depth.
- typically have rapid onset and recovery

Question 19

Define complicated variable decels

Answer 19

Variable decels with the following additional features which increase the likelihood of fetal hypoxia:
- Rising baseline rate
- Reducing or absent baseline variability.
- baseline fetal tachycardia.
- Slow return to baseline FHR after the end of the contraction.
- Large amplitude (by 60 bpm or to 60 bpm) and/or long duration
(60 seconds).
- a smooth post deceleration overshoot
- a slow return to the baseline after the contraction
- Presence of smooth post deceleration overshoots (temporary smooth increase in FHR above baseline).

Question 20

Define prolonged decels

Answer 20

A fall in the baseline fetal heart rate for more than 90 seconds and up to 5 minutes

Question 21

Define bradycardia

Answer 21

A fall in the baseline fetal heart rate for more than 5 minute

Question 22

Define late decels and state what causes them.

Answer 22

Uniform, repetitive decreasing of FHR with, usually, slow onset mid to end of the contraction and nadir more than 20 seconds after the peak of the contraction and ending after the contraction.

= decelerations of any depth are significant if the fetus is hypoxic

In the presence of a non-accelerative trace with baseline variability <5 bpm, the definition would include decelerations of <15 bpm.

Cause: contractions in the presence of hypoxia

Question 23

What is the criteria for a normal antenatal trace?

Answer 23

• A baseline fetal heart rate of 110‐160 bpm
• Normal baseline variability ≥ 6bpm and ≤ 25bpm
• 2 accelerations within a 20 minute period (reactivity)
• No decelerations

Question 24

What is the criteria for a normal intrapartum trace?

Answer 24

• A baseline fetal heart rate of 110‐160 bpm
• Normal baseline variability ≥ 6bpm and ≤ 25bpm
• accelerations
• no decels

Question 25

What does normal baseline variability indicate?

Answer 25

Normal baseline variability represents the continuous
interaction and balancing between the
- sympathetic nervous system
- parasympathetic nervous system

Normal baseline variability is therefore highly indicative of adequate CNS oxygenation

Question 26

What does a normal vs abnormal trace indicate?

Answer 26

Normal trace-> well oxygenated fetus
Abnormal trace-> 60% ‐ 70%+ false positive
rate for hypoxia

Question 27

What causes a bradycardia?

Answer 27

• maternal hypotension
• prolonged umbilical cord compression
• uterine hyperstimulation
• sustained fetal hypoxia of any cause

Question 28

What causes a base line bradycardia?

Answer 28

• a mature parasympathetic system
• fetal heart conduction defect

Question 29

What is the difference between a baseline brady and a brady?

Answer 29

A baseline bradycardia is a baseline that is below 110 BPM.
A Bradycardia is a fall in baseline of FHR for more than 5 minutes.

Question 30

Define a tachycardia

Answer 30

A baseline fetal heart rate of more than 160 bpm

This range of baseline, is not associated with hypoxia in the presence of accelerations or with normal variability and no decelerations

Question 31

What can cause a tachycardia?

Answer 31

• maternal tachycardia
• maternal fever (dehydration is a complicating
  factor)
• drugs e.g. salbutamol, terbutaline, atropine
• fetal tachyarrhythmia
• infection e.g. chorioamnionitis
• hypoxia (mild and compensating)

Question 32

What causes Prolonged decels?

Answer 32

• hypoxia

that results from;
- prolonged contractions
- epidural insertion
- uterine hyperstimulation
- supine hypotension
- ruptured uterus
- abruption
- VE

*significance depends don’t he clinical picture

Question 33

Explain how a contractions compromises a fetus

Answer 33

• Contraction onset
• reduced in intervillious space blood flow
• Insufficient O2 transfer into the fetus
• fetal O2 reaches a level low enough to result in myocardial depression
• deceleration occurs after the onset of the conraction
• uterine contraction begins to subside
• intervillous space blood flow improves
• fetal O2 levels begin to rise
• FHR returns to baseline after the contraction has finished

Question 34

What CTG feature is indicative of sever fetal anemia?

Answer 34

Sinusoidal patterns

Question 35

What must be included in a CTG report?

Answer 35

Baseline: the rate should be recorded
Baseline variability: normal, reduced, absent or
increased
Accelerations: present or absent
Decelerations: type, frequency, depth and duration
Uterine activity: frequency, strength, duration and rest
Management, including escalation