FETAL MONITORING

REASONS TO MONITOR THE FETUS

ANTENATAL:

1. MATERNAL INDICATIONS e.g. obstetric cholestasis2. FETAL INDICATIONS e.g. reduced fetal movements, 3. PLACENTAL INDICATIONS e.g. placental insufficiency /

growth restriction

IN LABOUR:

1. LOW RISK PATIENT2. HIGH RISK PATIENT

ANTENATAL FETAL MONITORING

BIOPHYSICAL PROFILE USS: 1. Breathing - Does the baby have breathing movements at least once in 30 minutes?2. Body Movement - Does the baby move at least three times in 30 minutes?3. Muscle Tone - Does the baby have at least one flexion-extension (open-close)

movement of arms, legs or hands in 30 minutes?4. Amount of amniotic fluid - Is there enough fluid around the baby?

5. CTG: Is it reactive?

AMNIOTIC FLUID

The Amniotic Fluid Index (AFI) can be used to determine fetal well-being.Most of the fluid in amniotic fluid is contributed to by fetal urine.This is then resorbed by the membranes and umbilical cord Rapid turnover - possible to measure amniotic fluid from one day to the next

OBSERVATION NORMAL (2 POINTS) ABNORMAL (0 POINTS)

CTG (NON-STRESS TEST) REACTIVE NON-REACTIVE

FETAL BREATHINGONE BREATHING PERIOD

LASTING AT LEAST 60 SECNO BREATHING OBSERVED

FETAL MOVEMENTS

3 DISCRETE AND

DEFINTE MOVEMENTS OF

ARMS LEGS OR BODY

LESS THAN 3 DISCRETE

MOVEMENTS

FETAL TONE

ARMS & LEGS FLEXED.

ONE DEFINITE EXTENSION /

RETURN TO FLEXION

NO FLEXION

AMNIOTIC FLUID

LARGEST POCKET OF FLUID

MORE THAN 1cm WITHOUT

LOOPS OF CORD

LARGEST POCKET OF FLUID

LESS THAN 1cm WITHOUT

LOOPS OF CORD

BIOPHYSICAL PROFILE SCORE

8-10 = maximal score0-4 = severe fetal compromise; delivery indicated

Doppler blood flow velocity waveforms

Non-invasive velocity measurements of blood flow

Fetus is completely dependent on the supply of oxygen and nutrients from the placenta

Examination of the blood flow through the umbilical circulation can assess fetal health

Increased placental vascular resistance, reduces velocity of the end-diastolic flow in the umbilical cord artery

Several Doppler indices have been used to quantify abnormalities in umbilical arteryDoppler flow waveforms: A/B ratio, the resistance index, the pulsatility index

Placental insufficiency can be quantified based on the reduction of end-diastolic Doppler flow velocity into (1) reduced enddiastolic flow velocity, (2) absent end-diastolic flow velocity, and(3) reversed end-diastolic flow velocity.

DOPPLER WAVEFORMS

Middle cerebral artery peak-systolic flow velocity (MCA-PSV) use Doppler to detect fetal anaemia

Doppler blood flow velocity waveforms

Ductus Venosus Dopplers• May be used as a trigger for delivery of IUGR fetus.May be used as a trigger for delivery of IUGR fetus.• Late sign of CV decompensationLate sign of CV decompensation• Reflects decreased ability to handle venous return.Reflects decreased ability to handle venous return.• Precedes FHR decelsPrecedes FHR decels• Present in 79/211 (37%) of preterm IUGRPresent in 79/211 (37%) of preterm IUGR, u, useful > seful > 29wks 29wks • Predictive of pH<7.2 Predictive of pH<7.2

Baschat, O&G, 2007

MONITORING IN LABOUR

Intermittent auscultation recommended for low-risk women in established labour

INDICATIONS FOR continuous EFM:

1. meconium-stained liquor, 2. abnormal FHR detected by intermittent auscultation 3. maternal pyrexia 4. fresh bleeding in labour5. oxytocin use for augmentation6. the woman’s request.

FETAL PHYSIOLOGY1. The fetal heart pumps deoxygented blood to the placenta via the two umbilical arteries2. At the placenta there is a free exchange of blood gases

(there's no mixing of foetal/maternal blood)3. The blood is pumped back to the fetus via a single umbilical vein

The fetal heart is regulated by: 1. Nerve supply

i.e. HR is reduced by vagus nerve (parasympathetic), increased by sympathetic supply2. Circulating catecholamines3. Central nervous system activity

These are influenced by changes in:1. fetal BP2. fetal blood gas levels (O2, CO2, pH) 3. Hypoxia4. Pyrexia5. Drugs6. Gestation7. Cord compression8. Cerebral activity

FETAL HEART RATE

A: Fetal heartbeat; B: Indicator showing movements felt by mother (caused by pressing a button); C: Fetal movement; D: Uterine contractions

FeatureBaseline (bpm) Variability (bpm) Decelerations Accelerations

Reassuring 110–160 ≥ 5 None Present

Non-reassuring100–109161–180

< 5 for 40–90 minutes

Typical variable decelerations with over 50% of contractions, occurring for over 90 minutesSingle prolonged deceleration for up to 3 minutes The absence

of accelerations

with otherwise

normal trace is

of uncertain

significance

Abnormal

< 100> 180Sinusoidal pattern ≥ 10 minutes

< 5 for 90 minutes

Either atypical variable decelerations with over 50% of contractions or late decelerations, both for over 30 minutesSingle prolonged deceleration for more than 3 minutes

Classification of FHR trace features

Category Definition

NormalAn FHR trace in which all four features are classified as reassuring

SuspiciousAn FHR trace with one feature classified as non-reassuring and

the remaining features classified as reassuring

PathologicalAn FHR trace with two or more features classified as non-reassuring or one or more classified as abnormal

Definition of normal, suspicious and pathological FHR traces

Classifications of CTG’S 1) Normal: Implies fetal well-being 2) Suspicious: Indicates continued observation /additional tests 3) Pathological: Mandatory Action.

SMALL GROUP / PAIR WORKSHOP

using

FRESH EYES LABELS

DR. C BRAVADO

Define Risk: Low or High Contractions: Frequency, Length Baseline Rate: Bradycardia, Normal, Tachycardia Variability: 5-10bpm/min Accelerations: Present or Absent Decelerations: Present or Absent, Type Outcome: Normal, Suspicious. Pathological.

Management Plan

FBS result (pH) Interpretation

≥ 7.25 Normal FBS

FBS should be repeated if the FHR abnormality persists within 60 minutes or within 30 minutes if FHR pattern deteriorates

7.21–7.24 Borderline FBS

Repeat FBS within 30 minutes or consider delivery if rapid fall since last sample

≤ 7.20 Abnormal FBS

Delivery indicated

The classification of fetal blood sample (FBS) results

APGAR SCORES

DESIGNED TO ASSESS WHICH BABIES NEED RESUSCITATION;

IT DOESN'T TELL US WHY A BABY NEEDS RESUSCITATION

0 1 2

colour blue/pale all over Blue extremities, body pink

No cyanosis, Body/extremities pink

HR 0 <100 >100

Reflex irritability No response grimace/feeble cry

cry/pull away when stimulated

Tone none Some flexionFlexed arms & legs, resist extension

Breathing absent Irregular, gasping Strong, lusty cry

CORD GASES

Indication of:

1. how well the oxygen supply has been maintained to the fetus during labour

2. How well the fetus has eliminated the waste product CO2

Gives an indication of the efficiency of placental gas exchange during labour

Cord gases can suggest a baby has been deprived of oxygen during labour but it cannot tell us if the baby has suffered harm as a result

A baby could have good Apgars despite abnormal cord gases

A baby that has been deprived of oxygen during labour may have compensated well but is still at risk of of e.g. hypoglycaemia

SMALL GROUP WORKSHOP

Divide up into 4 groups

Read through the case history

Using DR C BRAVADO review the CTG at the times indicated in BOLD

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