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Radiology
Doppler Ultrasound of the Uterine Artery
Built from Obstetric Imaging
What’s inside
7 sections · 67 slides
Overview
- Scope of this presentation
- Terms used throughout
Uteroplacental circulation and abnormal placentation
Why a vessel outside the uterus reports on the placenta inside it
- Spiral arteries of the endometrium
- Trophoblast remodelling of the spiral arteries
- Consequences of spiral artery conversion
- Impaired trophoblastic invasion in preeclampsia and growth restriction
- Fall in impedance with advancing gestation
- Histological correlation with placental bed biopsy
- Classification of preeclampsia by gestation at delivery
- Screening target of uterine artery Doppler
First-trimester measurement technique
How the pulsatility index is obtained at the 11 to 13+6 week scan
- Two-stage model of preeclampsia and the window for prevention
- Standard sagittal approach to the uterine artery
- Pulsed wave Doppler settings for uterine artery sampling
- Machine settings for uterine artery Doppler
- Uterine artery at the level of the internal os
- Normal uterine artery Doppler waveform
- Reading the uterine artery waveform
- Transverse approach as an alternative
- Transverse technique for uterine artery pulsatility index
- Sagittal versus transverse approach: reported equivalence
- Transvaginal measurement technique
- Paracervical vascular plexus on transvaginal scanning
- Difference between transabdominal and transvaginal pulsatility index
Second-trimester and third-trimester measurement
Measuring later when the first-trimester chance was missed
- Indications for later-trimester measurement
- Transabdominal technique in the second and third trimesters
- Uterine artery crossing the external iliac vessels
Sampling site, reproducibility and quality assurance
What makes the pulsatility index reliable enough to screen with
- Sampling site dependence of pulsatility index and peak systolic velocity
- Peak systolic velocity as a check on sampling position
- Intersonographer variation in pulsatility index measurement
- Effect of operator feedback on screening performance
- Audit of operator performance in a first-trimester cohort
- Maternal factors affecting uterine artery pulsatility index
- Direction of effect of maternal characteristics
- Expressing pulsatility index in multiples of the median
- Uterine artery Doppler in twin pregnancies
Screening for preeclampsia and fetal growth restriction
What the test actually detects, trimester by trimester
- Detection rate and false-positive rate defined
- First-trimester uterine artery Doppler used alone
- Fetal Medicine Foundation first-trimester screening algorithm
- Components of the combined first-trimester model
- ASPRE study screening performance
- 62%
- Aspirin in high-risk pregnancies identified by screening
- External validation of the Fetal Medicine Foundation algorithm
- 41.3%
- Combined screening applied to twin pregnancies
- Aspirin in multiple pregnancies
- Diastolic notching of the uterine artery waveform
- Likelihood ratios for uterine artery Doppler in the second trimester
- Multicentre second-trimester screening at 23 weeks
- Second-trimester versus first-trimester prediction
- Third-trimester combined screening at 30 to 33+6 weeks
- Adding placental growth factor and soluble fms-like tyrosine kinase-1
- Third-trimester Doppler in suspected small for gestational age fetuses
- Screening performance across the three trimesters
Conclusions and practice points
Where uterine artery Doppler now sits in clinical care
- Historical development of the marker
- Limitation of stand-alone second-trimester screening
- Shift toward first-trimester combined algorithms
- Requirements for accurate and reproducible measurement
- Key points
- Practical checklist for measuring uterine artery pulsatility index
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition