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 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 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 thethan 1% chance of developing either pre-eclampsia or havehaving IUGR . A high resistance often equates to a 70% chance of pre-eclampsia and 30% chance of IUGR.
Radiographic assessment
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 flow throughout pregnancy
- persistence of notching throughout pregnancy
- reversal of diastolic flow throughout pregnancy: severe state
See also
-<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 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 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 the 1% chance of developing either <a href="/articles/pre-eclampsia">pre-eclampsia</a> or have <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 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 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>