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USS tests of fetal wellbeing. USS tests of fetal wellbeing. Amniotic fluid assessment Biophysical profile Umbilical artery doppler Umbilical vein doppler (Uterine artery doppler) (Mean cerebral artery (MCA) doppler). Amniotic Fluid assessment. Must not contain umbilical cord
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USS tests of fetal wellbeing • Amniotic fluid assessment • Biophysical profile • Umbilical artery doppler • Umbilical vein doppler • (Uterine artery doppler) • (Mean cerebral artery (MCA) doppler)
Amniotic Fluid assessment • Must not contain umbilical cord • Deepest pocket • <2cm (oligo) or >8cm (poly) • AFI • <5th centile for gestational age (oligo) • >95th centile for gestational age (poly) • <5.1cm • Subjective assessment by experienced operator
Indications • IUGR • Reduced fetal movements • Post dates pregnancy
Biophysical ProfileHistory • Screened out anomalies • Alternative to Oxytocin Challenge Test Contraction Stress test • Arbitrary Scoring-no reason for the “weighting” some components maybe more important than others • Limited evidence to support its use • Normal result useful for 24 hours
Indications • Post dates pregnancy • IUGR • Reduced fetal movements • Maternal hypertension
Parameters of Biophysical scoring • CTG • 2 accs with mvmts in 20mins • FBMs • >1episode of 30s in 30min-not continuous • Gross body/limb mvmts • 3 mvmts in 30mins-continuous • Tone/posture • 1 episode flexion-extension-flexion of limb,opening hand, mouth, trunk rotation • AFV • 1pool >2cms X 2cm
Tips for best assessment process • Do CTG first • Assess fetal state, do when fetus “awake” • Transverse fetal abdomen image with limbs • Score out of 10 - without CTG it is incomplete • USS part 0,2,4,6 or 8/8 • 6 or 8/8 normal • BUT for amniotic fluid ALWAYS an abnormal result
DOPPLER IN OBSTETRICS • Flow velocity waveform-spectral display • Influenced by cardiac function vessel wall characteristics viscosity downstream vascular arrangement
DOPPLER IN PREGNANCYKEY POINTS • Need to understand basic principles • Is user dependent • Established roles fetal welfare assessment assessment of anaemia fetal echocardiography • Potential roles screening for preeclampsia uses for venous doppler • Fetal circulation has low resistance throughout absent or reversed velocities abnormal
UMBILICAL ARTERIAL DOPPLER • Mid portion of cord • In fetal quiescence • Use RI or PI • Progressive fall in resistive indices throughout normal pregnancy • Angle, sample volume important • Extremes of fetal heart rate will affect result
S = peak systolic frequencies D = least diastolic frequencies S-D/S = resistance or Pourcelot index S-D/mean = Pulsatility index (S/D = s d ratio, cannot describe AEDV ) These are gestation dependent the trend is important
Use of Umbilical Arterial Doppler in high risk pregnancy (preeclampsia and SGA) • 30% reduction in perinatal death • 40% reduction in admissions • deliveries< 34 weeks • No differences in C/S or fetal distress in labour Cochrane review2000
Fetal growth restriction Fetal “overgrowth”
Normal Spiral Arteriole Thin walled Abnormal Spiral Arteriole Thick walled
FETAL VENOUS DOPPLER • Venous Doppler a marker of fetal cardiac dysfunction influenced by fetal behavioural state esp FBM • Umbilical vein non pulsatile pulsatile decreased forward flow at end diastole • Ductus Venosus “M” shaped waveform reversed velocities abnormal proposed uses TTTS aneuploidy screening 1st T anaemia
FETAL DOPPLER SUMMARY • Umbilical artery well assessed • Trend through gestation important • Absent end diastolic velocities or reversed velocites always abnormal • Doppler does not tell when delivery should occur • Later in gestation fetus less tolerant of abnormal Doppler • Pulsatile umbilical vein may be preterminal
UTERINE ARTERY FLOW VELOCITY WAVEFORMSUpper panel normal waveform Lower panel abnormal with notching
Uterine arterial dopplera problem of a low prevalence condition • Poor predictor of preterm birth Ultrasound Obstet Gynecol. 2004 Sep;24(4):Second-trimester uterine artery Doppler and spontaneous preterm delivery.Cobian-Sanchez F, Prefumo F, Bhide A, Thilaganathan B. • Poor predictor of PET, FGR P.N.Mortality. BJOG. 2000 Feb;107(2):196-208How useful is uterine artery Doppler flow velocimetry in the prediction of pre-eclampsia, intrauterine growth retardation and perinatal death? An overview.Chien PF, Arnott N, Gordon A, Owen P, Khan KS.
USS tests of fetal wellbeing • Amniotic fluid assessment • Biophysical profile • Umbilical artery doppler • Umbilical vein doppler • (Uterine artery doppler) • (Mean cerebral artery (MCA) doppler)