Cerebroplacental ratio
Updates to Article Attributes
Cerebroplacental ratio (CPR) is an obstetric ultrasound tool used as a predictor of adverse pregnancy outcome in both small for gestational age (SGA) and appropriate for gestational age (AGA) fetuses. An abnormal CPR reflects redistribution of cardiac output to the cerebral circulation, and has been associated with intrapartum fetal distress, increased rates of emergency caesarean and NICU admissions and poorer neurological outcomes.
It is calculated by dividing the Doppler pulsatile indicespulsatility index of the middle cerebral artery (MCA) by the umbilical artery (UA). pulsatility index:
CPR = MCA PI / UA PI
The index will reflect mild increasedincrease in placental resistance with mild reductions in the fetal brain vascular resistance. An abnormal cerebroplacental ratio may result in the following conditions:
Practical points
- low normal range MCA and upper normal range UA PI
- abnormal low MCA and normal UA PI
- abnormal low MCA and high UA PI
CPR is an earlier markerIt follow then that detection of growth restriction
Various studies have variably defined the threshold of abnormal CPR as either ratio <1ref, ratio <1.08ref, in terms of MoMref or based on centiles. The only longitudinal study known to the article editor at the time of writing defines abnormal CPR as <5th centile2.
-<p><strong>Cerebroplacental ratio (CPR) </strong>is an important <a title="Second trimester ultrasound scan" href="/articles/second-trimester-ultrasound-scan">obstetric ultrasound</a> tool used as a predictor of adverse pregnancy outcome and is calculated by dividing the Doppler pulsatile indices of the <a title="Fetal middle cerebral artery pulsatility index" href="/articles/fetal-middle-cerebral-artery-pulsatility-index">middle cerebral artery (MCA)</a> by the umbilical artery (UA).</p><p>The index will reflect mild increased in placental resistance with mild reductions in the fetal brain vascular resistance. </p><h4>Practical points</h4><ul><li><p>CPR is an earlier marker of <a title="Intra uterine growth restriction" href="/articles/intrauterine-growth-restriction">growth restriction</a> </p></li></ul>- +<p><strong>Cerebroplacental ratio (CPR) </strong>is an <a href="/articles/second-trimester-ultrasound-scan">obstetric ultrasound</a> tool used as a predictor of adverse pregnancy outcome in both small for gestational age (SGA) and appropriate for gestational age (AGA) fetuses. An abnormal CPR reflects redistribution of cardiac output to the cerebral circulation, and has been associated with intrapartum fetal distress, increased rates of emergency caesarean and NICU admissions and poorer neurological outcomes. </p><p>It is calculated by dividing the Doppler pulsatility index of the <a href="/articles/fetal-middle-cerebral-artery-pulsatility-index">middle cerebral artery (MCA)</a> by the umbilical artery (UA) pulsatility index:</p><p>CPR = MCA PI / UA PI</p><p>The index will reflect mild increase in placental resistance with mild reductions in the fetal brain vascular resistance. An abnormal cerebroplacental ratio may result in the following conditions:</p><ul>
- +<li>low normal range MCA and upper normal range UA PI</li>
- +<li>abnormal low MCA and normal UA PI</li>
- +<li>abnormal low MCA and high UA PI</li>
- +</ul><p>It follow then that detection of perinatal risk based on CPR may occur in the setting of reassuring UA PI (but abnormal MCA), or even if both UA and MCA PI are within the normal range. </p><p>Various studies have variably defined the threshold of abnormal CPR as either ratio <1<sup>ref</sup>, ratio <1.08<sup>ref</sup>, in terms of MoM<sup>ref</sup> or based on centiles. The only longitudinal study known to the article editor at the time of writing defines abnormal CPR as <5th centile<sup>2</sup>.</p>
References changed:
- 2. Ebbing C, Rasmussen S, Kiserud T. Middle cerebral artery blood flow velocities and pulsatility index and the cerebroplacental pulsatility ratio: longitudinal reference ranges and terms for serial measurements. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 30 (3): 287-96. <a href="https://doi.org/10.1002/uog.4088">doi:10.1002/uog.4088</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/17721916">Pubmed</a> <span class="ref_v4"></span>
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