1. Fetal Wellbeing and Antenatal Monitoring
Radha Venkatakrishnan
Clinical Lecturer
Warwick Medical School

2. Antenatal Monitoring
Why?
Who?
How?

3. Why? Two thirds of fetal deaths occur before the onset of labor.
Many antepartum deaths occur in women at risk for uteroplacental insufficiency.
Ideal test: allows intervention before fetal death or damage from asphyxia.
Preferable: treat disease process and allow fetus to go to term.

4. Antenatal monitoring Uteroplacental insufficiency
Inadequate delivery of nutritive or respiratory substances to appropriate fetal tissues.
Inadequate exchange within the placenta due to decreased blood flow, decreased surface area or increased membrane thickness.
Inadequate maternal delivery of nutrients or oxygen to the placenta or to problems of inadequate fetal uptake.

5. Antenatal monitoring Theoretical scheme of fetal deterioration
Fetal well being
Fetal growth retardation (Marginal placental respiratory function)
Fetal hypoxia with stress (Decreasing respiratory function)
Some residual effects of intermittent hypoxia (profound respiratory compromise)
Asphyxia
Death

6. Who? Conditions placing the fetus at risk for UPI
Preeclampsia, chronic hypertension,
Collagen vascular disease, diabetes mellitus, renal disease,
Fetal or maternal anemia, blood group sensitization,
Hyperthyroidism, thrombophilia, cyanotic heart disease,
Postdate pregnancy,
Fetal growth restriction

7. How? Methods for antepartum fetal assessment Fetal movement counting
Assessment of uterine growth
Antepartum fetal heart rate testing
Biophysical profile
Doppler velocimetry

8. Fetal movement counting
Maternal perception of a decrease in fetal movements / change in the pattern of fetal movements may be a sign of impending fetal compromise.
Cardiff “count to ten” : 10 movements in 12 hours.
Kick charts
No robust evidence.

9. Reduced fetal movements
First episode: monitoring by CTG
Persistent: USS for growth, LV & UAD, CTG 2 to 3 times per week
Absent :
No FH: confirm by USS
FH present: growth scan and UAD

10. Tests for RFM Cochrane data for CTG
Increased hospitalisation, additional tests & elective delivery
No benefit in outcome
Interpretation errors
False reassurance
UAD has been shown to be predictive of perinatal compromise in high risk pregnancies

11. Symphysiofundal height
General rule: fundal height in centimeters will equal the weeks of gestation.
Exceptions: maternal obesity, multiple gestation, polyhydramnios, abnormal fetal lie, oligohydramnios, low fetal station, and fetal growth restriction.
Customized chart :Abnormalities of fundal height should lead to further investigation.
Accuracy: poor?

12. Antenatal CTG
Initial observational studies showed a strong correlation between the abnormal CTG and poor fetal outcome
Widely used as the primary method of
antenatal fetal assessment
Poor predictive value
High inter-observer inconsistencies

13. Antenatal CTG
Healthy fetuses display normal oscillations and fluctuations of the baseline FHR (Hammacher, 1966; Kubli, 1969).
Absence of these patterns was associated with increase in neonatal depression and perinatal mortality.
Accelerations of the FHR during stress testing correlated with fetal well being (Trierweiler, 1976).

14. Antenatal CTG
Accelerations of the FHR occur with fetal movement, uterine contractions, or in response to external stimuli.
FHR accelerations appear to be a reflection of CNS alertness and activity.
Absence of FHR accelerations seems to depict CNS depression caused by hypoxia, drugs, fetal sleep, or congenital anomalies.

15. CTG monitor
Cochrane:
Antenatal CTG has no significant effect on perinatal outcome or interventions such as early elective delivery
NICE:
Evidence does not support the routine use of antenatal electronic fetal heart rate monitoring for fetal assessment in women with an uncomplicated pregnancy and therefore it should not be offered

17. Decelerations Decelerations- transient slowing of FHR below the
baseline level of
more than 15 bpm
and lasting for 15 s
or more

18. Antenatal CTG Perinatal mortality: 6.2/1000 False positive rate: 50%
False negative rate: 3.2 / 1000

19. Ultrasound

20. Ultrasound Quick, non-invasive procedure, easy interpretation
Customised fetal growth charts (serial scans)
Liquor volume
Placental function
Doppler study
Abnormal results correlate with increased risk of stillbirth and neonatal morbidity in selected pregnancies

21. Biophysical profile Described by Manning (1980)
The number of biophysical activities that could be recorded increased with real time ultrasound:
Fetal movement (FM)
Fetal tone (FT)
Fetal breathing movements (FB)
Amniotic fluid volume (AFV)

22. Variables measured CTG: reactive – as described earlier.
FBM: present - at least 1 episode of at least 30 seconds duration (within a 30 minute period).
FM: present - at least 3 discrete episodes.
FT: normal - at least 1 episode of extension of extremities or spine with return to flexion.
AFV: normal – largest pocket of fluid greater than 1 cm in vertical diameter.

23. Scoring Biophysical profile (BPP) Each variable When normal: 2
When abnormal: 0
Highest Score: 10, Lowest Score: 0
Accuracy improved by increasing the number of variables assessed.
Overall false negative rate: 0.6/1000

24. BPP and Perinatal morbidity
Significant inverse linear correlation (Manning, 1990)
Fetal distress
NICU admission
IUGR
5 min Apgar <7
Cord artery pH <7.20

25. Cochrane
Not enough evidence to evaluate the use of biophysical profile as a test of fetal well-being in high risk pregnancies except diabetes
No evidence of any benefit in screening
Errors associated with the BPP
Management decisions based on the score only.
Intervention based on a false positive low score
No intervention based on a false negative normal score
Management based on BPP without considering overall clinical findings.

26. Doppler velocimetry
40% of combined ventricular output is directed to the placenta by umbilical arteries.
Assessment of umbilical blood flow provides information on blood perfusion of the fetoplacental unit.
Volume of flow increases and vascular impedance decreases with advancing Doppler velocimetry of the umbilical arteries gestational age.
Low vascular impedance allows a continuous forward blood flow throughout the cardiac cycle.

27. Doppler study Doppler velocimetry
An increase in the vascular resistance of the fetoplacental unit leads to a decrease in end diastolic flow velocity or its absence in the flow velocity waveform.
Abnormal waveforms reflect the presence of a structural placental lesion.
Abnormal Doppler results require specific management protocols and intensive fetal surveillance.

28. Doppler velocimetry
Uterine arteries – 24/40

29. Doppler velocimetry Umbilical arteries Middle cerebral artery
Ductus venosus

30. Doppler study Doppler velocimetry
A poor indicator of fetal compromise or adaptation to the placental abnormality but does identify patients at risk for increased perinatal mortality.
Strong association between high systolic to diastolic ratios and IUGR.

31. In summary
Why?
Who?
How?

32. THANK YOU