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 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 Profile History 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 PREGNANCY KEY 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

Umbilical Doppler

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 assessment

UTERINE ARTERY FLOW VELOCITY WAVEFORMS Upper panel normal waveform Lower panel abnormal with notching

Uterine arterial doppler a 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):196-208 How 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)