Uteroplacental blood flow assessment
Updates to Article Attributes
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 assessmentfeatures
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 = (peak systolic velocity - end diastolic velocity) / time averaged velocity = (PSV - EDV) / TAV
Abnormal patterns include
- persistence of a high resistance flows throughout pregnancy
- persistence of notching throughout pregnancy
- reversal of diastolic flow throughout pregnancy: severe state
-<p><strong>Uteroplacental blood flow assessment</strong> is an important part of fetal well-being assessment and evaluates Doppler flow in the <a href="/articles/uterine-artery">uterine arteries</a> and rarely the <a href="/articles/ovarian-artery">ovarian arteries</a>.</p><h4>Pathology</h4><p>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 <a href="/articles/uterine-artery-flow-notching">notch</a> may be present.</p><p>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 <a href="/articles/pre-eclampsia">pre-eclampsia</a> and <a href="/articles/iugr">IUGR</a>. If resistance is low, it has an excellent <a href="/articles/negative-predictive-value">negative predictive value</a> with a less than 1% chance of developing either <a href="/articles/pre-eclampsia">pre-eclampsia</a> or having <a href="/articles/iugr">IUGR</a> . A high resistance often equates to a 70% chance of pre-eclampsia and 30% chance of IUGR.</p><h4>Radiographic assessment</h4><h5>Ultrasound</h5><p>The parameters used in the assessment of uteroplacental blood flow include:</p><ul>- +<p><strong>Uteroplacental blood flow assessment</strong> is an important part of fetal well-being assessment and evaluates Doppler flow in the <a href="/articles/uterine-artery">uterine arteries</a> and rarely the <a href="/articles/ovarian-artery">ovarian arteries</a>.</p><h4>Pathology</h4><p>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 <a href="/articles/uterine-artery-flow-notching">notch</a> may be present.</p><p>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 <a href="/articles/pre-eclampsia">pre-eclampsia</a> and <a href="/articles/iugr">IUGR</a>. If resistance is low, it has an excellent <a href="/articles/negative-predictive-value">negative predictive value</a> with a less than 1% chance of developing either <a href="/articles/pre-eclampsia">pre-eclampsia</a> or having <a href="/articles/iugr">IUGR</a> . A high resistance often equates to a 70% chance of pre-eclampsia and 30% chance of IUGR.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>The parameters used in the assessment of uteroplacental blood flow include:</p><ul>
-</ul><h6>Resistive index (RI)</h6><p>This is calculated by the following equation</p><p><strong>RI = (PSV-EDV) / PSV</strong> = (peak systolic velocity - end diastolic velocity) / peak systolic velocity </p><ul>- +</ul><h6>Resistive index (RI)</h6><p>This is calculated by the following equation:</p><p><strong>RI = (PSV-EDV) / PSV</strong> = (peak systolic velocity - end diastolic velocity) / peak systolic velocity </p><ul>