Fetal Wellbeing and Fetal Wellbeing and Antenatal MonitoringAntenatal Monitoring

Radha VenkatakrishnanRadha VenkatakrishnanClinical LecturerClinical Lecturer

Warwick Medical SchoolWarwick Medical School

Antenatal Monitoring Antenatal Monitoring

Why?Why?

Who?Who?

How?How?

Why?Why?• Two thirds of fetal deaths occur before Two thirds of fetal deaths occur before

the onset of labor.the onset of labor.• Many antepartum deaths occur in Many antepartum deaths occur in

women at risk for uteroplacental women at risk for uteroplacental insufficiency.insufficiency.

• Ideal test: allows intervention before Ideal test: allows intervention before fetal death or damage from asphyxia.fetal death or damage from asphyxia.

• Preferable: treat disease process and Preferable: treat disease process and allow fetus to go to term.allow fetus to go to term.

Antenatal monitoringAntenatal monitoring• Uteroplacental insufficiencyUteroplacental insufficiency

– Inadequate delivery of nutritive or Inadequate delivery of nutritive or respiratory substances to appropriate respiratory substances to appropriate fetal tissues.fetal tissues.

– Inadequate exchange within the Inadequate exchange within the placenta due to decreased blood flow, placenta due to decreased blood flow, decreased surface area or increased decreased surface area or increased membrane thickness.membrane thickness.

– Inadequate maternal delivery of Inadequate maternal delivery of nutrients or oxygen to the placenta or nutrients or oxygen to the placenta or to problems of inadequate fetal to problems of inadequate fetal uptakeuptake..

Antenatal monitoringAntenatal monitoring• Theoretical scheme of fetal deteriorationTheoretical scheme of fetal deterioration

– Fetal well being Fetal well being – Fetal growth retardation (Marginal Fetal growth retardation (Marginal

placental respiratory function)placental respiratory function)– Fetal hypoxia with stress (Decreasing Fetal hypoxia with stress (Decreasing

respiratory function)respiratory function)– Some residual effects of intermittent Some residual effects of intermittent

hypoxia (profound respiratory hypoxia (profound respiratory compromise)compromise)

– AsphyxiaAsphyxia– DeathDeath

Who?Who?• Conditions placing the fetus at risk for UPIConditions placing the fetus at risk for UPI

– Preeclampsia, chronic hypertension,Preeclampsia, chronic hypertension,– Collagen vascular disease, diabetes Collagen vascular disease, diabetes

mellitus, renal disease,mellitus, renal disease,– Fetal or maternal anemia, blood group Fetal or maternal anemia, blood group

sensitization,sensitization,– Hyperthyroidism, thrombophilia, Hyperthyroidism, thrombophilia,

cyanotic heart disease,cyanotic heart disease,– Postdate pregnancy,Postdate pregnancy,– Fetal growth restrictionFetal growth restriction

How?How?• Methods for antepartum fetal Methods for antepartum fetal

assessmentassessment– Fetal movement countingFetal movement counting– Assessment of uterine growthAssessment of uterine growth– Antepartum fetal heart rate testingAntepartum fetal heart rate testing– Biophysical profileBiophysical profile– Doppler velocimetryDoppler velocimetry

Fetal movement countingFetal movement counting• Maternal perception of a decrease in Maternal perception of a decrease in

fetal movements / change in the fetal movements / change in the pattern of fetal movements may be a pattern of fetal movements may be a sign of impending fetal compromise.sign of impending fetal compromise.

• Cardiff “count to ten” : 10 movements Cardiff “count to ten” : 10 movements in 12 hours.in 12 hours.

• Kick chartsKick charts• No robust evidenceNo robust evidence..

Reduced fetal movementsReduced fetal movements• First episode: monitoring by CTG 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

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

Symphysiofundal heightSymphysiofundal height• General rule: fundal height in centimeters General rule: fundal height in centimeters

will equal the weeks of gestation.will equal the weeks of gestation.• Exceptions: maternal obesity, multiple Exceptions: maternal obesity, multiple

gestation, polyhydramnios, abnormal fetal gestation, polyhydramnios, abnormal fetal lie, oligohydramnios, low fetal station, and lie, oligohydramnios, low fetal station, and fetal growth restriction.fetal growth restriction.

• Customized chart :Abnormalities of fundal Customized chart :Abnormalities of fundal height should lead to further investigation.height should lead to further investigation.

• Accuracy: poor?Accuracy: poor?

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

Antenatal CTGAntenatal CTG• Healthy fetuses display normal Healthy fetuses display normal

oscillations and fluctuations of the oscillations and fluctuations of the baseline FHR (Hammacher, 1966; Kubli, baseline FHR (Hammacher, 1966; Kubli, 1969).1969).

• Absence of these patterns was Absence of these patterns was associated with increase in neonatal associated with increase in neonatal depression and perinatal mortality.depression and perinatal mortality.

• Accelerations of the FHR during stress Accelerations of the FHR during stress testing correlated with fetal well being testing correlated with fetal well being (Trierweiler, 1976).(Trierweiler, 1976).

Antenatal CTGAntenatal CTG• Accelerations of the FHR occur with Accelerations of the FHR occur with

fetal movement, uterine contractions, fetal movement, uterine contractions, or in response to external stimuli.or in response to external stimuli.

• FHR accelerations appear to be a FHR accelerations appear to be a reflection of CNS alertness and activity.reflection of CNS alertness and activity.

• Absence of FHR accelerations seems to Absence of FHR accelerations seems to depict CNS depression caused by depict CNS depression caused by hypoxia, drugs, fetal sleep, or hypoxia, drugs, fetal sleep, or congenital anomalies. congenital anomalies.

CTG monitorCTG monitor•Cochrane:

– Antenatal CTG has no significant effect on perinatal outcome or interventions such as early elective delivery

• NICE:NICE:– Evidence does not support the routine Evidence does not support the routine

use of antenatal electronic fetal heart use of antenatal electronic fetal heart rate monitoring for fetal assessment in rate monitoring for fetal assessment in women with an uncomplicated women with an uncomplicated pregnancy and therefore it should not pregnancy and therefore it should not be offered be offered

DecelerationsDecelerations• Decelerations- Decelerations-

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

Antenatal CTGAntenatal CTG• Perinatal mortality: 6.2/1000Perinatal mortality: 6.2/1000• False positive rate: 50%False positive rate: 50%• False negative rate: 3.2 / 1000False negative rate: 3.2 / 1000

Ultrasound

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

Biophysical profileBiophysical profile• Described by Manning (1980)Described by Manning (1980)• The number of biophysical activities The number of biophysical activities

that could be recorded increased that could be recorded increased with real time ultrasound: with real time ultrasound: – Fetal movement (FM)Fetal movement (FM)– Fetal tone (FT)Fetal tone (FT)– Fetal breathing movements (FB)Fetal breathing movements (FB)– Amniotic fluid volume (AFV)Amniotic fluid volume (AFV)

Variables measuredVariables measured• CTG: reactive – as described earlier.CTG: reactive – as described earlier.• FBM: present - at least 1 episode of at FBM: present - at least 1 episode of at

least 30 seconds duration (within a 30 least 30 seconds duration (within a 30 minute period).minute period).

• FM: present - at least 3 discrete episodes.FM: present - at least 3 discrete episodes.• FT: normal - at least 1 episode of FT: normal - at least 1 episode of

extension of extremities or spine with extension of extremities or spine with return to flexion.return to flexion.

• AFV: normal – largest pocket of fluid AFV: normal – largest pocket of fluid greater than 1 cm in vertical diameter.greater than 1 cm in vertical diameter.

ScoringScoring• Biophysical profile (BPP)Biophysical profile (BPP)

– Each variable Each variable •When normal: 2When normal: 2•When abnormal: 0When abnormal: 0

– Highest Score: 10, Lowest Score: 0Highest Score: 10, Lowest Score: 0– Accuracy improved by increasing the Accuracy improved by increasing the

number of variables assessed.number of variables assessed.– Overall false negative rate: 0.6/1000Overall false negative rate: 0.6/1000

BPP and Perinatal morbidityBPP and Perinatal morbidity• Significant inverse linear correlation Significant inverse linear correlation

(Manning, 1990)(Manning, 1990)•Fetal distressFetal distress•NICU admissionNICU admission•IUGRIUGR•5 min Apgar <75 min Apgar <7•Cord artery pH <7.20Cord artery pH <7.20

• 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 BPPErrors associated with the BPP– Management decisions based on the score Management decisions based on the score

only.only.•Intervention based on a false positive low Intervention based on a false positive low

scorescore•No intervention based on a false negative No intervention based on a false negative

normal scorenormal score– Management based on BPP without Management based on BPP without

considering overall clinical findings.considering overall clinical findings.

Doppler velocimetryDoppler velocimetry– 40% of combined ventricular output is 40% of combined ventricular output is

directed to the placenta by umbilical directed to the placenta by umbilical arteries.arteries.

– Assessment of umbilical blood flow Assessment of umbilical blood flow provides information on blood perfusion of provides information on blood perfusion of the fetoplacental unit.the fetoplacental unit.

– Volume of flow increases and vascular Volume of flow increases and vascular impedance decreases with advancing impedance decreases with advancing Doppler velocimetry of the umbilical Doppler velocimetry of the umbilical arteries gestational age.arteries gestational age.

– Low vascular impedance allows a Low vascular impedance allows a continuous forward blood flow throughout continuous forward blood flow throughout the cardiac cycle.the cardiac cycle.

Doppler studyDoppler study• Doppler velocimetryDoppler velocimetry

– An increase in the vascular resistance of An increase in the vascular resistance of the fetoplacental unit leads to a the fetoplacental unit leads to a decrease in end diastolic flow velocity or decrease in end diastolic flow velocity or its absence in the flow velocity its absence in the flow velocity waveform.waveform.

– Abnormal waveforms reflect the Abnormal waveforms reflect the presence of a structural placental lesion.presence of a structural placental lesion.

– Abnormal Doppler results require Abnormal Doppler results require specific management protocols and specific management protocols and intensive fetal surveillance.intensive fetal surveillance.

Doppler velocimetryDoppler velocimetry• Uterine arteries – 24/40Uterine arteries – 24/40

Doppler velocimetryDoppler velocimetry• Umbilical arteriesUmbilical arteries• Middle cerebral arteryMiddle cerebral artery• Ductus venosusDuctus venosus

Doppler studyDoppler study• Doppler velocimetryDoppler velocimetry

– A poor indicator of fetal compromise or A poor indicator of fetal compromise or adaptation to the placental abnormality adaptation to the placental abnormality but does identify patients at risk for but does identify patients at risk for increased perinatal mortality.increased perinatal mortality.

– Strong association between high systolic Strong association between high systolic to diastolic ratios and IUGR.to diastolic ratios and IUGR.

In summaryIn summary

Why?Why?

Who?Who?

How?How?

THANK YOUTHANK YOU