Fetal monitoring and growth restriction Flashcards
Purpose of monitoring the fetus
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
What does fetal monitoring look for
Antepartum - Uteroplacental Insufficiency or fetal abnormalities
Peri-partum - fetal compromise
Patients at risk of Uteroplacental insufficiency
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
Signs of fetal compromise (6)
Reduced fetal movement Suspected IUGR Recurrent APH Recurrent UTI Oligo or polyhydramnios Fetal abnormality
Problems associated with a small baby
Antepartum stillbirth
fetal distress during birth and asphyxia
Neo/post-natal complications (SIDS, disability, etc)
In adult life –>HTN, NIDDM,etc
Problems associated with a large baby
Antepartum diabetes or polyhydramnios
Difficult Labour or birth trauma for mother or baby
neonatal complications and mortality
In adult life –> T2DM, CV problems, etc
How does nutrient excess cause problems?
Heightened myocardial activity causing hypertrophy, causing relative hypoxia leading to acidosis, ischaemia and decompensation
Increased GFR causes polyhydramnios
How does nutrient deficit cause problems?
Reduction in growth of non-vital organs causing future disability and hypoxia leading to acidosis, ischaemia and decompensation
Reduced GFR leads to oligohydramnios
Monitoring for chronic vs acute events
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)
How do we monitor the fetus antepartum?
Clincally –> symphyseal-fundal height, FMs
Biophysically –> CTG, USS, UAD
Invasively –> amniocentesis or CVS
Maternal perception of fetal movements
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
Fetal movement counting
more than 10 in 12hrs is good
No predictive value in monitoring
Maternal subjective assessment is better
Symphyseal-fundal height
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
Types of SGA fetus
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
Ultrasound measurements of fetal size
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
Amniotic fluid volume (AFI)
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,
Umbilical artery dopler
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
CTG
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)
Decelerations
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
Accelerations
Indicate a healthy baby preparing for a challenge (contraction or fetal movements). this indicates healthy coupling between the heart and brain
Reassuring CTG features
a baseline rate of 110-160, variablity over 5, no decelerations but accelerations
Non-reassuring CTG features
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
Abnormal CTG features
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
Categories of CTG trace
Normal –> all features reassuring
Suspicious –> one non-reassuring feature but the rest reassuring
Pathological –> Two or more non-reassuring or one abnormal
Dr C Bravado
Define risk Contractions Baseline variability Accelerations Decelerations Overall
Merits of CTG
no contraindications + rarely equivocal
<1% test unsatisfactory & can be performed as OP
Most predictive when normal
Problems with CTG
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
Invasive testing
Useful for antenatal diagnosis/karyotyping
Good when non-invasive tests are inconclusive but require specialist centres
Peripartum monitoring
Intermittent Auscultation (IA)
Continuous EFM/CTG
Fetal Blood sample (FBS)
Intermittent Auscultation (IA)
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
Continuous EFM/CTG
Most widely used method of monitoring during labour - interpretation as above
Fetal Blood sample (FBS)
Only useful in severe situations but a good way to see if the fetus is really in distress
Continuous EFM/CTG vs Intermittent Auscultation (IA)
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
Fetal Sleep on CTG
reduced variablity and possibly reduced baseline rate
Maternal Pyrexia on CTG
Sustained fetal tachycardia
Fetal Echocardiography
Used in women at high risk of fetal cardiac abnormalities.
Fetal Biophysical profile
Used to look at fetal movements, breathing and other factors which indicate the neurological state and tone of the fetus
Abdominal Diameter
The most acurrate estimator of Fetal weight and growth or detecting IUGR,
