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 beingFetal growth retardation (Marginal placental respiratory function)Fetal hypoxia with stress (Decreasing respiratory function)Some residual effects of intermittent hypoxia (profound respiratory compromise)AsphyxiaDeath
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 growthAntepartum fetal heart rate testingBiophysical profileDoppler 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 chartsNo robust evidence.
9 Reduced fetal movements First episode: monitoring by CTGPersistent: USS for growth, LV & UAD, CTG 2 to 3 times per weekAbsent :No FH: confirm by USSFH present: growth scan and UAD
10 Tests for RFM Cochrane data for CTG Increased hospitalisation, additional tests & elective deliveryNo benefit in outcomeInterpretation errorsFalse reassuranceUAD 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 CTGInitial observational studies showed a strong correlation between the abnormal CTG and poor fetal outcomeWidely used as the primary method ofantenatal fetal assessmentPoor predictive valueHigh inter-observer inconsistencies
13 Antenatal CTGHealthy 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 CTGAccelerations 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 monitorCochrane:Antenatal CTG has no significant effect on perinatal outcome or interventions such as early elective deliveryNICE: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
20 Ultrasound Quick, non-invasive procedure, easy interpretation Customised fetal growth charts (serial scans)Liquor volumePlacental functionDoppler studyAbnormal 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: 0Highest Score: 10, Lowest Score: 0Accuracy 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 distressNICU admissionIUGR5 min Apgar <7Cord artery pH <7.20
25 CochraneNot enough evidence to evaluate the use of biophysical profile as a test of fetal well-being in high risk pregnancies except diabetesNo evidence of any benefit in screeningErrors associated with the BPPManagement decisions based on the score only.Intervention based on a false positive low scoreNo intervention based on a false negative normal scoreManagement based on BPP without considering overall clinical findings.
26 Doppler velocimetry40% 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.
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.