Uteroplacental blood flow assessment
- Integral Diagnostics, Shareholder (ongoing)
- Micro-X Ltd, Shareholder (ongoing)
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<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
-<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 pre-eclampsia or having IUGR . 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>- +<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 <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.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>The parameters used in the assessment of uteroplacental blood flow include:</p><ul>
- +<li><p><strong>RI</strong> = <a href="/articles/resistive-index-vascular-ultrasound">resistive index</a></p></li>
- +<li><p><strong>PI</strong> = <a href="/articles/pulsatility-index-ultrasound">pulsatility index</a></p></li>
- +<li><p>presence of persistent diastolic notching</p></li>
- +</ul><h6>Resistive index (RI)</h6><p>This is calculated by the following equation:</p><p><strong>RI = (PSV-EDV) / PSV</strong> = (<a href="/articles/peak-systolic-velocity-doppler-ultrasound">peak systolic velocity</a> - <a href="/articles/end-diastolic-velocity-doppler-ultrasound">end-diastolic velocity</a>) / peak systolic velocity </p><ul>
- +<li><p>normal (low resistance) RI <0.55</p></li>
-<strong>RI</strong> = <a href="/articles/resistive-index-vascular-ultrasound">resistive index</a>-</li>-<li>-<strong>PI</strong> = <a href="/articles/pulsatility-index-ultrasound">pulsatility index</a>-</li>-<li>presence of persistent diastolic notching</li>-</ul><h6>Resistive index (RI)</h6><p>This is calculated by the following equation:</p><p><strong>RI = (PSV-EDV) / PSV</strong> = (<a href="/articles/peak-systolic-velocity-vascular-ultrasound">peak systolic velocity</a> - <a href="/articles/end-diastolic-velocity-vascular-ultrasound">end-diastolic velocity</a>) / peak systolic velocity </p><ul>-<li>normal (low resistance) RI <0.55</li>-<li>high resistance<ul>-<li>bilateral <a href="/articles/uterine-artery-flow-notching">notches</a> RI >0.55</li>-<li>unilateral <a href="/articles/uterine-artery-flow-notching">notches</a> RI >0.65</li>- +<p>high resistance</p>
- +<ul>
- +<li><p>bilateral <a href="/articles/uterine-artery-flow-notching">notches</a> RI >0.55</p></li>
- +<li><p>unilateral <a href="/articles/uterine-artery-flow-notching">notches</a> RI >0.65</p></li>
-</ul><h6>Pulsatility index (PI)</h6><p>This is calculated by the following equation:</p><ul><li>-<strong>PI =</strong> <strong>(PSV - EDV) / TAV</strong> = (peak systolic velocity - end-diastolic velocity) / time-averaged velocity</li></ul><h6>Abnormal patterns include</h6><ul>-<li>persistence of a high resistance flow throughout pregnancy</li>-<li>persistence of notching throughout pregnancy</li>-<li>reversal of diastolic flow throughout pregnancy: severe state</li>- +</ul><h6>Pulsatility index (PI)</h6><p>This is calculated by the following equation:</p><ul><li><p><strong>PI =</strong> <strong>(PSV - EDV) / TAV</strong> = (peak systolic velocity - end-diastolic velocity) / time-averaged velocity</p></li></ul><h6>Abnormal patterns include</h6><ul>
- +<li><p>persistence of a high resistance flow throughout pregnancy</p></li>
- +<li><p>persistence of notching throughout pregnancy</p></li>
- +<li><p>reversal of diastolic flow throughout pregnancy: severe state</p></li>