Fetal monitoring

Question 1

sleeping fetus CTG

Answer 1

Less variability and higher baseline as decreased parasympathetic activation
sleep wake cycle or 20-40 minutes

Question 2

How does gestation affect baseline

Answer 2

premature - sympathetically dominant - higher baseline

term /post term - more parasympathetic so lower baseline

Question 3

variability definition

Answer 3

3 to 5 cycles per minute fluctuations in the range of 6-25 bpm in amplitude
Reflects the balance between sympathetic and parasympathetic stimulation

Question 4

Accelerations vs reactivity

Answer 4

Fetal response to stimulation and are transient increase in FHR of 15 bpm above the baseline for 15 seconds or more
Reactivity is the presence of two or more accelerations in twenty minutes
Intrapartum does not have to have reactivity

Question 5

features that we are monitoring maternal HR

Answer 5

poor quality recording, sudden change in baseline, change in recording style, accelerations with contractions
Usually taken from the uterine artery
Acceleration with contraction as increased preload from redistribution of blood from the myometrium

Question 6

Conservative management of abnormal CTG

Answer 6

Continue the monitoring
Consider the complete clinical picture
Identify reversible causes - positioning, hyperstimulation, hypotension
Give time for management to work 
Escalation of care
Consider further evaluation

Question 7

tachysystole definition + management

Answer 7

more then 5 active labour contractions over 10 minutes without fetal heart rate abnormalities

continuous CTG, reduce or stop oxytocin, 1:1 care, notify snr, consider tocolysis

Question 8

Uterine hypertonus definition + management

Answer 8

contractions lasting more then 2 minutes or occuring within 60 seconds of each other without FHR abnormalities

continuous CTG, reduce or stop oxytocin, 1:1 care, notify snr, consider tocolysis

Question 9

Uterine hyperstimulation definition + management

Answer 9

tachysystole or hypertonus with FHR abnormalities

continuous CTG, reduce or stop oxytocin, 1:1 care, notify snr, consider tocolysis / urgent delivery

Question 10

tocolysis options

Answer 10

250 mcg terbutaline IV or SC
IV salbutamol 100 mcg
Sublingual GTN 400 mcg

Question 11

what affects variability

Answer 11

Sleep
Sedation -medications pethidine, morphine, fentanyl, MgSO4
Prematurity
Hypoxia

Question 12

What causes a low baseline

Answer 12

postdates
Profound hypoxia eg cord compression and bradycardia
drugs - high dose B Blockers suppress sympathetic innervation so have a lower baseline
fetal conduction defects / heart block

Question 13

What causes baseline tachycardia

Answer 13

Maternal fever
Drugs - terbutaline or salbutamol
Fetal infection eg chorio
Premature fetus
hypoxia
fetal tachyarrhythmias

Question 14

Decelerations - definition

Early

Answer 14

normal physiological response to mild increases in intracranial pressure from head compression, and reflex drp in FHR - uniform in shape and finish with the contraction
occur in sleep phase, 4-8 cm, mimic the contraction

Question 15

Variable decelerations

Answer 15

Caused by cord compression
Vary in depth, duration timing
cord compression -> fall in oxygen -> reflex parasympathetic response -> Acetylcholine released -> fall in FHR
Thought is to reduce myocardial workload to reduce ischemia

Question 16

Shouldering physiology

Answer 16

As the compression starts, thin walled veins compress first, therefore reduction of blood to the heart, reduced oxygenation, so sympathetic response increases FHR
As it compresses the umbilical artery, O2 drops, detected by chemoreceptors ACH released, though vagal nerve (parasynpathetic) and rapid fall in FHR.
The artery opens first as the contraction eases, (thicker wall) withdrawn of vagus nerve as now low pressures, and if there is still venous compression the reduced R atrial pressures trigger a sympathetic response - shouldering
Shouldering is a normal physiologica lresponse and represents a well oxygenated fetus

Question 17

When are variable complicated

Answer 17

Rising baseline
reduced variability
Persistent large amplitude >60 bpm OR to 60 bpm and long duration > 60 seconds
Smooth post deceleration overshoot - completely sympathetic dominant as no oxygen left after contraction, so is smooth
Slow return to baseline
Loss of shouldering (no longer in guideline)

Question 18

Prolonged deceleration definition and causes

Answer 18

between 90 seconds and 5 minutes
Caused by hypoxia
- maternal hypotension, hypertonus / tachysystole / supine / abruption / rupture

Question 19

Late decelerations

Answer 19

Contractions in the presence of hypoxia
Start after the start of the contraction and the peak is 20 seconds after the peak of the contraction
Uniform and repetitive

Question 20

Sinusoidal pattern

Answer 20

Smooth and regular oscillating pattern - not necessarily regular in amplitude but in timing of oscillations
rate 2-5 cycles per minute at an amplitude of 5-15 bpm from baseline
Sign of anaemia
Loss of autonomic control

pseudosinusoidal - not as smooth or regular, prior normal trace, ? thumb sucking

Question 21

How to perform intermittent auscultation

Answer 21

at least every 30 minutes in first stage (from 4 cm)

and After each contraction in second stage or at least every 5 minutes in second stage

Question 22

Indications for intrapartum CTG

Answer 22

abnormal dopplers IUGR
RFM within 1 week of labour
APH intrapartum bleed 
Abnormal antenatal CTG
Oligo or polyhydramnios / no liquor at ARM
>37 or <42 weeks
IOL / augmentation 
Abnormal contractions
Abnormal progress 
Maternal pyrexia, HTN, PET VBAC BMI over 40 
Abn fetal screening PAPP A
diabetes + macrosomia OR medicated OR poor control  
Epidural 
Breech
Multiple pregnancy
Fetal abnormality

Question 23

Contraindications to FBS include?

Answer 23

Contraindications to FBS include:
- Evidence of serious, sustained fetal compromise.
- Risk of fetal bleeding disorders (e.g. fetal thrombocytopenia,
haemophilia).
- Non-vertex presentation.
- Maternal infection
* (e.g. HIV, hepatitis B, hepatitis C, active
primary herpes and suspected fetal sepsis).
*Group B
Streptococcus carrier status does not preclude FBS.

Not recommended <34 weeks

Question 24

When should paired umbilical cord lactates be performed?

Answer 24

Paired umbilical cord blood gas or lactate analysis should be taken at delivery either routinely or where any of the following are
present:
- Apgar score < 4 at 1 minute.
- Apgar score < 7 at 5 minutes.
- Fetal scalp sampling performed in labour.
- Operative delivery undertaken for fetal compromise