uteroplacental blood flow assessment
Uteroplacental blood flow assessment is an important part of fetal well-being assessment and evaluates Doppler flow in the uterine arteries and rarely the ovarian arteries.
Pathology
In a non-gravid state and at the very start of pregnancy the flow in the uterine artery is of high pulsatility with a high systolic flow and low diastolic flow. A physiological early diastolic notch may be present.
Resistance to blood flow gradually drops during gestation as a greater trophoblastic invasion of the myometrium takes place. An abnormally high resistance can persist in pre-eclampsia and IUGR. If resistance is low, it has an excellent negative predictive value with a less than 1% chance of developing either pre-eclampsia or having IUGR . A high resistance often equates to a 70% chance of pre-eclampsia and 30% chance of IUGR.
Radiographic features
Ultrasound
The parameters used in the assessment of uteroplacental blood flow include:
- RI = resistive index
- PI = pulsatility index
- presence of persistent diastolic notching
Resistive index (RI)
This is calculated by the following equation:
RI = (PSV-EDV) / PSV = (peak systolic velocity - end-diastolic velocity) / peak systolic velocity
- normal (low resistance) RI <0.55
- high resistance
Pulsatility index (PI)
This is calculated by the following equation:
- PI = (PSV - EDV) / TAV = (peak systolic velocity - end-diastolic velocity) / time-averaged velocity
Abnormal patterns include
- persistence of a high resistance flow throughout pregnancy
- persistence of notching throughout pregnancy
- reversal of diastolic flow throughout pregnancy: severe state
Siehe auch:
- Dopplersonographie der Nabelarterie
- Intrauterine Wachstumsretardierung
- ovarian artery
- abnormal ductus venosus waveforms
- absent umbilical arterial end diastolic flow
- fetal MCA Doppler assessment
- umbilical venous flow assessment
- Arteria uterina
- reversal of umbilical artery end diastolic flow
- ductus venosus flow assessment
- notch
- notches
und weiter:
Assoziationen und Differentialdiagnosen zu uterine arterial Doppler ultrasound assessment:
