Fetal monitoring and growth restriction

Question 1

Purpose of monitoring the fetus

Answer 1

To distinguish low risk from high risk pregnancies
To minimize the risk of fetal death by optimizing the timing and mode of delivery
To avoid unnecessary interventions

Question 2

What does fetal monitoring look for

Answer 2

Antepartum - Uteroplacental Insufficiency or fetal abnormalities
Peri-partum - fetal compromise

Question 3

Patients at risk of Uteroplacental insufficiency

Answer 3

Early or late labour, multiple pregnancies 
Pre-eclampsia or other medical disorders
Previous IUGR or still birth
Extreme maternal age or weight
Low maternal social class or drug use

Question 4

Signs of fetal compromise (6)

Answer 4

Reduced fetal movement
Suspected IUGR
Recurrent APH
Recurrent UTI
Oligo or polyhydramnios
Fetal abnormality

Question 5

Problems associated with a small baby

Answer 5

Antepartum stillbirth
fetal distress during birth and asphyxia
Neo/post-natal complications (SIDS, disability, etc)
In adult life –>HTN, NIDDM,etc

Question 6

Problems associated with a large baby

Answer 6

Antepartum diabetes or polyhydramnios
Difficult Labour or birth trauma for mother or baby
neonatal complications and mortality
In adult life –> T2DM, CV problems, etc

Question 7

How does nutrient excess cause problems?

Answer 7

Heightened myocardial activity causing hypertrophy, causing relative hypoxia leading to acidosis, ischaemia and decompensation
Increased GFR causes polyhydramnios

Question 8

How does nutrient deficit cause problems?

Answer 8

Reduction in growth of non-vital organs causing future disability and hypoxia leading to acidosis, ischaemia and decompensation
Reduced GFR leads to oligohydramnios

Question 9

Monitoring for chronic vs acute events

Answer 9

Chronic events are easily picked up but it is hard to predict the risk of acute events (abruption, cord prolapse, uterine rupture, hypotension, uterine hypertony)

Question 10

How do we monitor the fetus antepartum?

Answer 10

Clincally –> symphyseal-fundal height, FMs
Biophysically –> CTG, USS, UAD
Invasively –> amniocentesis or CVS

Question 11

Maternal perception of fetal movements

Answer 11

felt from 20wks in primips and 16 to 18 weeks in multips
15% of women feel reduced FMs –> if >24hrs risk of fetal death
Can also be: fetus sleeping, maternal sedatives, maternal distractions, obesity or polyhydramnios

Question 12

Fetal movement counting

Answer 12

more than 10 in 12hrs is good
No predictive value in monitoring
Maternal subjective assessment is better

Question 13

Symphyseal-fundal height

Answer 13

Useful if done serially, properly from 24wks
can be effected by: fetal lie, maternal BMI, parity and ethnicity, No of fetuses, volume of amnion and any uterine or ovarian masses
No evidence that it can rule out SGA or LGA

Question 14

Types of SGA fetus

Answer 14

Asymmetric IUGR is usually imposed by uteroplacental insufficiency
Symmetric IUGR is 3/4 just a constituionally small baby, 1/4 is due to genetic/chromosomal abnormality or in-utero insult

Question 15

Ultrasound measurements of fetal size

Answer 15

Biparietal diameter (BPD), Head circumference (HC), abdo circumference (AC) or femur length (FL)
AC is best predictor of EFW, and together they are the best predictor of SGA
Serial measurements are best

Question 16

Amniotic fluid volume (AFI)

Answer 16

Any single vertical pool should be 2-8cm - outside this range mortality is high
The sum of four pools should be 5-20cm
Oligohydramnios can cause cord compression leading to variable Decels,

Question 17

Umbilical artery dopler

Answer 17

Not for screening use but useful in high risk women and reduces interventions and improves outcomes
Has a saw tooth pattern with continuous forward flow, there is a risk of IUGR if there is reduced, absent or reversed end diastolic flow

Question 18

CTG

Answer 18

Shows both FHR and uterine contractions
Should have a base line of 110-160 with 5-15bpm variability which is under autonomic control
Accelerations or decelerations (15x15) occur under somatic control in response to stresses (contractions)

Question 19

Decelerations

Answer 19

Can be early (occuring with a contraction and >30seconds in length), late (after a contraction and >30seconds in length) or variable (random and shorter)
Healthy babies will ‘shoulder’ decelerations

Question 20

Accelerations

Answer 20

Indicate a healthy baby preparing for a challenge (contraction or fetal movements). this indicates healthy coupling between the heart and brain

Question 21

Reassuring CTG features

Answer 21

a baseline rate of 110-160, variablity over 5, no decelerations but accelerations

Question 22

Non-reassuring CTG features

Answer 22

a baseline rate outside 110-160, variablity less than 5 for 40-90mins,typical decelerations with 50% of contractions for >90mins or a single prolonged decel. may be some accelerations or absenta baseline

Question 23

Abnormal CTG features

Answer 23

a baseline rate of 180, reduced variablity >90mins, Either atypical decels with >50% of contractions or late decels, for >30mins OR a single decel of >3mins
No accelerations

Question 24

Categories of CTG trace

Answer 24

Normal –> all features reassuring
Suspicious –> one non-reassuring feature but the rest reassuring
Pathological –> Two or more non-reassuring or one abnormal

Question 25

Dr C Bravado

Answer 25

Define risk
Contractions
Baseline variability 
Accelerations
Decelerations
Overall

Question 26

Merits of CTG

Answer 26

no contraindications + rarely equivocal
<1% test unsatisfactory & can be performed as OP
Most predictive when normal

Question 27

Problems with CTG

Answer 27

Restricts maternal activity
Non-reassuring CTG - false positive rate of 75-90%
CTG changes usually occur late in FGR
Poor interpretation and leads to increased interventions

Question 28

Invasive testing

Answer 28

Useful for antenatal diagnosis/karyotyping

Good when non-invasive tests are inconclusive but require specialist centres

Question 29

Peripartum monitoring

Answer 29

Intermittent Auscultation (IA)
Continuous EFM/CTG
Fetal Blood sample (FBS)

Question 30

Intermittent Auscultation (IA)

Answer 30

useful in low risk women in established labour
1st stage–>listen after contractions for 1min every 15mins to construct an average
2nd stage–>same but every 5mins
Maternal pulse should be felt if any abnormality detected

Question 31

Continuous EFM/CTG

Answer 31

Most widely used method of monitoring during labour - interpretation as above

Question 32

Fetal Blood sample (FBS)

Answer 32

Only useful in severe situations but a good way to see if the fetus is really in distress

Question 33

Continuous EFM/CTG vs Intermittent Auscultation (IA)

Answer 33

CTG for high risk and IA for low risk
CTG reduces by 50% risk of neonatal seizures but increases the rate of inventions more
Both are acceptable

Question 34

Fetal Sleep on CTG

Answer 34

reduced variablity and possibly reduced baseline rate

Question 35

Maternal Pyrexia on CTG

Answer 35

Sustained fetal tachycardia

Question 36

Fetal Echocardiography

Answer 36

Used in women at high risk of fetal cardiac abnormalities.

Question 37

Fetal Biophysical profile

Answer 37

Used to look at fetal movements, breathing and other factors which indicate the neurological state and tone of the fetus

Question 38

Abdominal Diameter

Answer 38

The most acurrate estimator of Fetal weight and growth or detecting IUGR,