doppler and iugr • iugr - ucsf cme€¦ · 1 doppler and iugr danny wu, mbchb clinical instructor...

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1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences UCSF Outline Background of Doppler ultrasound • IUGR Fetal cardiovascular changes by Doppler – Arterial Umbilical artery Middle Cerebral Artery – Venous Ductus Venosus Physics of Doppler Ultrasound Doppler frequency shift v = fd.c / 2 ft.cos θ

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Page 1: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Doppler and IUGR

Danny Wu, MBChBClinical InstructorDivision of Maternal Fetal MedicineObstetrics, Gynecology and Reproductive SciencesUCSF

Outline

• Background of Doppler ultrasound• IUGR• Fetal cardiovascular changes by Doppler

– Arterial• Umbilical artery• Middle Cerebral Artery

– Venous• Ductus Venosus

Physics of Doppler Ultrasound

Doppler frequency shift

v = fd.c / 2 ft.cos θ

Page 2: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Doppler Ultrasound Safety in Pregnancy

• Diagnostic ultrasound is safe• Doppler ultrasound diagnostic equipment

has greater time-averaged intensities.• In vitro and animal experiments

– potential bio-effects by thermal, cavitational, or other mechanisms.

• ALARA principle (As Low As Reasonably Achievable)

In-utero Growth Restriction

• ACOG defined IUGR as EFW < 10th percentile• 4 million birth per year -- 400,0000 babies are

IUGR• Consequences

– At birth and in infancy– Childhood and adult life : Barker Hypothesis

• Risk of hypertension, hypercholesterolemia, coronary heart disease, impaired glucose tolerance and diabetes

• Enormous burden

Not All IUGR Are the Same

• Small for gestational age (SGA)– “constitutionally small”

• Pathologically small – Maternal illness present– Fetal pathology present

– No obvious reason

Page 3: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Optimal Timing of Delivery

• Despite over 10000 publications on the topic, confusion remains– Definition– IUGR is not a homogenous group – Mode of testing

• Timing of delivery for early IUGR is highly controversial

Fetal Circulation

Dopplers

placenta

ArterialUmbilical Artery

MCA

VenousUmbilical Vein

Ductus Venosus

Uterine artery

Umbilical Artery Doppler

Doppler waveform represents downstream impedance to flow

Page 4: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Doppler Waveform Analysis Normal Variations

• Gestational age– As GA advances, S/D declines

• Fetal heart rate– Negative correlation– If FHR 120-160, not significant variation

• Fetal breathing– Should perform sampling during fetal apnoea

• Site of sampling– Free loop preferred

GA

Umbilical artery Doppler

• As placental insufficiency worsens, diastolic flow progressively decreases

Morrow RJ; Adamson SL; Bull SB; Ritchie JW SOAm J Obstet Gynecol 1989 Oct;161(4):1055-60.

Decreased Absent Reversed

30% 70%Abnormal Vasculature

Page 5: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Absent End Diastolic Flow Reversed End Diastolic Flow

Perinatal Outcomes

• Absent or reversed flow is associated with adverse perinatal outcome

• It may be present for weeks before additional sign of fetal compromise occurs

Doppler in High Risk Pregnancy

• Eleven RCTs involving nearly 7000 women were included

• Reduction in perinatal deaths (OR 0.71)• Fewer inductions of labor (OR 0.83)• Fewer admissions to hospital • No difference fetal distress in labor• No difference caesarean delivery

Cochrane Database Syst Rev. 2000;(2):CD000073

Page 6: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Routine Doppler in Low Risk Pregnancy

• Not Recommended• Five trials were included which recruited

14,338 women

• No benefit

Cochrane Database Syst Rev. 2008

PhysiologicalChanges

Increased placental vascular resistance

Shunting to vital organs“Brain-sparing”

Impaired cardiacfunctions

UA S/D increases

MCA P/I decreases

Abnormal venous flow

Doppler Changes

MCA Doppler

Brain Sparing Effect

Cerebral Circulation“Brain Sparing Effect”

Cerebral Blood Flow

• Hypoxemia

• Hypoxemia + Acidemia

Page 7: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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MCA Doppler1. Fetus at rest2. Circle of Willis3. Zoom – MCA 50% of

screen4. Sample volume 1mm

placed between origin of carotid and the middle of the artery

5. Angle between USS and blood flow = 0°

6. Consistent waveforms7. Repeat 3 times

Doppler Waveform Analysis

Example of an MCA Doppler tracing at 27 weeksMiddle Cerebral Artery

IUGR

MCA PI PO2

MCA PI PO2 2 – 4 SD

MCA PI PO2 < 4 SD

Page 8: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Mari et al Ultrasound Obstet Gynecol 2007; 29:310-316

Mari et al Ultrasound Obstet Gynecol 2007; 29:310-316

MCA - PI or - PSV?

• MCA - PSV predicts perinatal mortality more accurately than MCA - PI

• Reason:– MCA - PI tends to normalize before delivery

or demise– MCA - PSV tends to slightly decrease just

before delivery or demise BUT it remains elevated

Venous Dopplers

Reflects fetal cardiac functionPredictive of adverse perinatal outcome

Page 9: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Ductus Venosus Qualitative Assessmnet

• Blood flow should always be antegrade

• Absent or reversed flow is alwaysabnormal

SD

A

Page 10: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Semi-quantitative Assessment Outcomes related to Doppler changes

Baschat et al Ultrasound Obstet Gynecol 2006; 27: 41–47

Venous Doppler abnormalityis the strongest predictor

Doppler Abnormality Perinatal Mortality

SD elevated 5.6%

AEDF/REDF 11.5%

Venous 38.8%

Baschat.Ultrasound Obstet Gynecol 2004; 23: 111–118

Arterial and venous Dopplers among IUGR fetuses

Baschat et al Ultrasound Obstet Gynecol 2006; 27: 41–47

Page 11: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Timing of Delivery

• Abnormal venous Doppler selects out the fetuses that are at highest risk

• Limited options:1) Wait2) Deliver

• Gestational age remains a major factor for adverse perinatal outcome especially in very preterm infants

Baschat et al Obstet Gynecol vol 109 , no.2(1), 2007

Intact Survival Neonatal Mortality

Page 12: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Other considerations

• Picconi et al 2008– 19 fetuses with IUGR followed prospectively– 14 fetuses demonstrated intermittent DVRF

with median time to delivery or death in 13 days (1-57 days)

– Among those with continuous : median interval of 7 days (1-23 days)

– Cord pH and BE available for 10 fetuse: • Only one had abnormal pH and another one with

BE

Sequence of Doppler Changes is Dependent on the Underlying Cause

Key Points

• IUGR is not a homogenous group• Doppler study to characterize fetal

cardiovascular changes offer promise when managing early IUGR

• Currently there is no good data on– What is the best test

– When is the best time

Page 13: Doppler and IUGR • IUGR - UCSF CME€¦ · 1 Doppler and IUGR Danny Wu, MBChB Clinical Instructor Division of Maternal Fetal Medicine Obstetrics, Gynecology and Reproductive Sciences

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Thank You