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Radiology
Doppler Ultrasound Evaluation of the Fetus and Placenta
Built from Obstetric Imaging
What’s inside
7 sections · 96 slides
Overview
- Purpose of Doppler ultrasound in pregnancy
- Scope of this presentation
- Divisions of Doppler assessment
- Vessels that can be interrogated in pregnancy
- Vessels used most often in routine practice
Arterial Doppler
What makes the shape of an arterial waveform, and how it is measured
- Determinants of the arterial flow waveform
- Peak systolic velocity
- End-diastolic velocity
- Physiological determinants of end-diastolic velocity
- Sequence from cardiac ejection to the diastolic trough
- Normal umbilical artery and umbilical vein waveform
- Reading the normal umbilical artery trace
- Insonation angle and the Doppler equation
- Practical limits of angle correction
- Absolute flow quantification versus semiquantitative indices
- The three angle-independent Doppler indices
- Why the pulsatility index is preferred
- Change in Doppler indices with gestational age
The Placental Circulation
Uterine artery Doppler on the maternal side, umbilical artery Doppler on the fetal side
- Two compartments of the placental circulation
- Uterine artery Doppler and its target vessels
- Uterine artery physiology in early pregnancy
- Trophoblastic transformation of the uterine vascular tree
- Normal progression of the uterine artery waveform
- Failure of normal uterine artery progression
- What umbilical artery Doppler measures
- Causes of raised umbilical artery impedance
- Umbilical artery waveforms in monochorionic twins
- Normal decline in umbilical artery indices
- Reserve of the villous circulation before Doppler changes
- Clinical meaning of the reserve
- Spectrum of umbilical artery waveforms
- Progression through the four umbilical artery patterns
- Umbilical artery waveform with increased resistance
- Absent end-diastolic velocity in the umbilical artery
- Reversed end-diastolic velocity in the umbilical artery
- Histologic basis of an abnormal umbilical artery index
- Fetal risks that track the degree of Doppler abnormality
- Place of umbilical artery Doppler in fetal assessment
The Fetal Cerebral Circulation
Middle cerebral artery indices, brain sparing, and peak systolic velocity
- What middle cerebral artery Doppler assesses
- Fetal middle cerebral artery on colour and spectral Doppler
- Brain sparing in the hypoxic fetus
- Interpreting brain sparing
- The cerebroplacental ratio
- Middle cerebral artery sampled with the beam parallel to flow
- Thick-walled immature villi and isolated brain sparing
- Value of the middle cerebral artery in late-onset growth restriction
- Fetal hypertension and cerebral flow indices
- Blood viscosity and middle cerebral artery peak systolic velocity
- Middle cerebral artery velocity measurement on the spectral trace
- Carbon dioxide as the physiologic regulator of MCA peak systolic velocity
Venous Doppler
The four-phase venous waveform, and what the ductus venosus reports
- Physiologic basis of the venous waveform
- Four phases of the venous waveform
- The S-wave
- The V-trough
- The D-wave
- The a-wave
- Pulsatility of central veins and the umbilical vein exception
- Ductus venosus sampling site and normal waveform
- Colour Doppler anatomy around the ductus venosus
- Landmarks around the ductus venosus
- Normal ductus venosus waveform with its four phases labelled
- Reading the normal ductus venosus trace
- Qualitative analysis of the ductus venosus waveform
- Factors that raise venous Doppler indices
- Absent and reversed a-wave in the ductus venosus
- Absent forward flow in the a-wave
- Reversed flow in the a-wave
- Interpreting an absent or reversed a-wave
- Structure of the venous Doppler indices
- Ductus Venosus Doppler Indices
- Ductus Venosus Doppler Indices (continued)
- Ductus venosus index formulas as printed
- Role of the ductus venosus in the fetal circulation
- Determinants of forward cardiac function
- Choosing between the a-wave and the V-wave
Technique
How each vessel is found, sampled and measured
- Conditions for any Doppler measurement
- Preparing the image before sampling
- Acquiring the spectral trace
- Sampling site for umbilical artery Doppler
- Uterine artery technique
- Middle cerebral artery technique
- Ductus venosus technique
- Avoiding contamination from neighbouring vessels
- Normal ductus venosus velocities and how to report them
Clinical Applications
Where Doppler changes what is actually done for a pregnancy
- Conditions in which Doppler ultrasound is used
- Purpose of serial Doppler assessment
- What the referring clinician needs to know
- Key points: arterial Doppler and the placenta
- Key points: venous Doppler and integration
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition