1.2 Foetal Surveillance

Question 1

Biophysical profile

Answer 1

Biophysical Profile - assesses acute fetal wellbeing through ultrasound. Takes about 30 mins to avoid sleep as a skew

Biophysical Profile (Score 2 or 0)
Foetal heart rate:
- 2 or more accelerations of 15 bpm for 15 seconds within 30 minutes
- 1 or no acceleration within 30 mins

Foetal muscle tone:
- 1 or more episodes of active extension and return to flexion in 30 mins
- Slow extension and return to partial or no flexion, no movement in 30 mins

Foetal body movements:
- 3 or more in 30 mins
- 2 or less in 30 mins

Foetal breathing movements:
- One or more episodes of FBM of >30 sec in 30 mins
- Absent or no episodes of FBM of >30 sec in 30 mins

Amniotic fluid volume:
- >5cm
- <5cm

Question 2

Uterine artery doppler studies

Answer 2

• Assesses the effectiveness of placentation and future risk of FGR
• placenta increases uterine blood flow from 60mls/min to 1000mls/min
• Placental insufficiency → unable to meet metabolic needs of foetus → FGR, increased risk of maternal preeclampsia
• Abnormal → high resistance uterine artery doppler study

Question 3

Umbilical artery doppler studies

Answer 3

• Assesses downstream placental vascular resistance
• Normal → low resistance fetoplacental circulation → maximum blood flow through placenta to deliver oxygen and remove waste → resistance decreases with increasing gestation due to vasodilation. Will show uniform doppler waveform
• Abnormal → increased placental vascular resistance → reduced placental gas and nutrient exchange → FGR
• Abnormal doppler waveform → high systolic and low diastolic ratio
• High systolic and below baseline diastolic = reverse flow

Question 4

Middle cerebral artery doppler studies

Answer 4

• Assesses growth-restricted foetus and can help show info on acute status of fetus
• With decreasing oxygen availability, the GRF prioritises blood flow to organs, the brain, and heart (a.k.a redistribution) but overtime can cause a reduced abdominal circumference with a normal head (a.k.a asymmetrical growth restriction)
• Normal MCA → high resistance
• Abnormal MCA → low resistance flow and increased diastolic flow → hypoxic

Question 5

Cerebroplacental ratio

Answer 5

• CPR is the ratio of MCA Doppler Pulsatility Index (PI) to the Umbilical Artery Doppler PI.
• Abnormal → <5th centile

Question 6

Ductus venosus doppler studies

Answer 6

• Ductus venosus - The blood vessel connecting the portal sinus (abdominal portion of umbilical vein)
• DV waveform reflects fetal heart function (specifically myocardial contractility) especially for early onset FGR
• Abnormal → increased resistance

Question 7

Fetal growth assessment (biometry)

Answer 7

• A healthy foetus should follow its centile growth trajectory across pregnancy (macrosomia or GR)
• Uses: informs us about future risks
• Limitations: requires accurate EDD, biparietal diameter, head circumference, abdominal circumference, and femur length to derive estimated fetal weight and can be inaccurate
• <5th centile is abnormal. Estimated fetal weight chart is also based on averages.

Question 8

Measuring amniotic fluid

Answer 8

• Generally done in 3rd trimester
• Woman must be positioned supine
• US Doppler placed over amniotic fluid pocket in a quadrant of the belly
• Vertical callipers measure the depth in centimetres of amniotic fluid (a.k.a deepest vertical pocket)
• Should not cross any foetal body part or umbilical cord (<5 or >25 abnormal)

Question 9

Intrapartum continuous CTG monitoring (antenatal & intrapartum risk factors)

Answer 9

Antenatal risk factors:
- Abnormal antenatal CTG
- Abnormal Doppler Umbilical Artery velocimetry
- Suspected or confirmed intrauterine growth restriction
- Prolonged pregnancy (>42 weeks)

Intrapartum risk factors:
- Induction of labour with prostaglandin/oxytocin
- Abnormal auscultation or CTG
- Regional anaesthesia
- Abnormal vaginal bleeding in labour

Question 10

Fetal scalp blood sampling in labour

Answer 10

A small scratch is made on the foetus’ head during labour to test the blood lactate of the baby, which will determine its wellbeing during delivery

<4.1 mmol/L then repeat in 1 hour → >5.8mmol/L or <7 mmol/L requires urgent assisted vaginal birth if possible or Category 1 C-section

Question 11

Fetal scalp blood sampling in labour - Indications & Contraindications

Answer 11

Indications:
- Bradycardia or complicated tachycardia
- Recurrent decelerations
- Prolonged loss of variability which does not spontaneously correct with fetal stimulation

Contraindications:
- Clear evidence on CTG of serious, sustained fetal compromise
- Maternal infection (Hep B, C, HIV, herpes, suspected intrauterine sepsis)
- Face, brow, or breech presentation

Question 12

Neonatal cord blood sampling

Answer 12

Determines foetal metabolic condition at the moment of birth and acid-base status. 12-16 mmol/L is associated with encephalopathy. Arterial vessel then vein

Testing can be delayed for a maximum of 90 minutes after birth for accurate results. Keep the umbilical cord clamped and at room temperature. Heparin syringe and cup of ice to preserve samples if needed. Label with baby’s details

Question 13

Neonatal cord blood sampling - indications, testing, report if

Answer 13

Indications:
- When clinicians are concerned about a potential fetal metabolic abnormality
- Preterm gestation
- Meconium stained liquor
- Assisted emergency birth (i.e., ventouse, instrumental, emergency c-section)

Testing:
- 10-20cm segment of cord double clamped
- Collect from the arterial cord vessels above the bottom clamp prior to collecting routine cord blood samples
OR
- Collect from the detached cord section

Report if:
- pH <7.15
- Base excess >-10
- Lactate >5
- Haemoglobin <140
- Glucose <3

Question 14

Abnormal fetal growth - macrosomia

Answer 14

A very large foetus (4000-4500g)

Causes: previous maternal history of it, pregnancy weight gain, parity, glucose intolerance, male foetus, and Beckwith-Widemann syndrome, TORCH infection

Risks: postpartum haemorrhage, vaginal lacerations, shoulder dystocia, lower APGAR

Question 15

Abnormal fetal growth - FGR

Answer 15

Infants with weights lower than expected (<10th centile) or significant drop in centiles

Short-term risks: infant may lack intrauterine reserves to undergo stress of labour

Long-term risks: cardiovascular disease, insulin resistance, obesity

Question 16

Detecting & managing FGA

Answer 16

Detection:
- fundal height measurement
- estimated foetal weight
- uterine arterial doppler studies
- MCA dopplers

Management:
- foetal surveillance

FGR Identification as per Safer Baby Bundle:
Level 1: No risk factors for FGR identified → standardised serial SFH measurement at each antenatal visit from 24 weeks gestation + US as clinically indicated
Level 2: Risk factor for FGR identified e.g., <20 or >40 y/o, IVF, high or low BMI, pregnancy substance use → FG US at 26-28 weeks and 34-36 weeks, additional US, SFH measurement
Level 3: High risk of early FGH identified e.g., previous early FGR, preeclampsia, previous stillbirth, maternal medical conditions → growth scans every 2-4 weeks from 24 weeks, low dose aspirin 150mg until 36 weeks to reduce risk of preterm preeclampsia

Question 17

Early & late onset FGR

Answer 17

Early FGR:
- FGR diagnosed <32 weeks gestation (easier to detect, harder to manage)
- 20-30% of FGR is early onset or 0.5-1% of all pregnancies
- Umbilical artery doppler will more likely show abnormalities

Late FGR:
- FGR diagnosed >32 weeks gestation (harder to detect but easier to manage)
- 70-80% FGR are late onset or 5-10% of pregnancies are late FGR
- Uterine artery doppler will more likely show abnormalities
- 2ml IM steroid injection for mum in buttock (before 36 weeks)
- In the event of preterm baby, most likely will not tolerate induction related hyperstimulation (synt, balloon, contractions) → have in mind emergency CAT

Question 18

Oligohydramnios

Answer 18

Oligohydramnios: less than expected amniotic fluid for gestational age. AFI <5cm

Causes:
- Fetal urinary tract abnormality, PPROM, twin-to-twin transfusion (anaemia), placental insufficiency, post-maturity (>42 weeks), placental abruption

Diagnosis:
- SFH < gestation, reduced DM, abdo palp (fetal parts easily felt)

Management:
- Investigate underlying cause, conservative vaginal delivery, optimise fetal/maternal outcome, maternal bed rest associated with improved liquor volume

Prognosis:
- Often poor if associated with PPROM or fetal abnormality
- Long-term oligo associated w) pulmonary hypoplasia

Question 19

Polyhydramnios

Answer 19

Polyhydramnios: more than expected amniotic fluid for gestational age. AFI >25cm

Causes:
- Multiple pregnancy (recipient twin), fetal abnormality of GIT, maternal diabetes, Rh Isoimmunisation, idiopathic

Diagnosis:
- US AFI >25cm, SFH > gestational age, fetus easily ballotable, fetal parts hard to palp, maternal symptoms associated w) increased uterine size (resp, GIT, vascular)

Management:
- Reductive amniocentesis, monitor, maternal medication (indomethacin), labour management

Complications:
- Prem labour, placental abruption, fetal abnormality, fetal malposition, macrosomia, cord prolapse (baby not engaged properly), postpartum uterine atony, SROM, breech/moving baby, decreased fetal movement

Question 20

Prevent stillbirth

Answer 20

Safer Baby Bundle Elements to reduce stillbirth risk after 28 weeks gestation
1. Supporting women to stop smoking in pregnancy
2. Improving screening and surveillance for foetal growth restrictions
3. Improving awareness and management of decreased foetal movement
4. Improving awareness of maternal safe sleeping position
5. Improving decision-making around timing of birth for women with risk factors