Diagnostic Performance of Cerebroplacental Ratio Thresholds at Term for Prediction of Low Birthweight and Adverse Intrapartum and Neonatal Outcomes in a Term, Low-Risk Population

Abstract

Objectives: To investigate the screening performance and best threshold centile (5th vs. 10th) of the cerebroplacental ratio (CPR) in low-risk, term pregnancies to predict low birthweight and adverse intrapartum and neonatal outcomes in a term, low-risk population. Methods: This was a blinded, prospective, cross-sectional study of low-risk singleton pregnancies at term. Women attended fortnightly from 36 weeks for CPR and estimated fetal weight assessment. Intrapartum and neonatal outcomes were recorded. Primary outcomes assessed were low birthweight, cesarean section for intrapartum fetal compromise, and composite adverse neonatal outcome. Results: A total of 483 women participated in the study. The CPR 10th centile (1.48) threshold resulted in the best screening performance. Sensitivities for low birthweight, cesarean section for intrapartum fetal compromise, and composite adverse neonatal outcome of 41.9, 61.1, and 38.3% were achieved for false-positive rates of 17.7, 17.7, and 15.2%, respectively. The corresponding areas under the receiver operating characteristic curves were 0.62, 0.72, and 0.62. Conclusion: The CPR 10th centile resulted in the best screening performance, although this would be considered fair at best. The CPR 10th centile may be useful as part of a risk stratification tool for prediction of low birthweight and adverse intrapartum and neonatal outcomes.

Correlation of Cerebroplacental Ratio (CPR) With Adverse Perinatal Outcome in Singleton Pregnancies

“…Furthermore, other authors have also confirmed that fetuses with an abnormal CPR that are appropriate for gestational age or have late-onset small gestational age SGA (>34 weeks of gestation) have a higher incidence of fetal distress in labor requiring emergency cesarean delivery (1,(9)(10)(11)(12)(13)(14)(15).…”

The physiology of intrapartum fetal compromise at term

“…More recently, the fetal cerebroplacental ratio (CPR) (ratio of the middle cerebral artery pulsatility index to the umbilical artery pulsatility index) has been proposed as a proxy for intrauterine growth with a low CPR indicative of suboptimal fetal growth. A low CPR (variably defined as <1.0, <5th centile, <10th centile, or <0.67 Multiples of Median [MoM]) 143,144 is associated with a range of adverse perinatal outcomes, including neonatal intensive care admission, acidosis, and emergency operative birth for IFC. 145,146 However, despite the broad association with adverse outcomes, the predictive utility of the CPR, particularly in a non-SGA cohort at term, remains modest, and caution should be exercised before incorporating its routine use into clinical care.…”

Diagnosis and surveillance of late-onset fetal growth restriction

“…Furthermore, some smaller prospective series on lowrisk populations also suggest this notion. 102 However, the clinical application of these findings remains to be determined. The largest prospective series on unselected pregnancies failed to find predictive value of CPR adverse outcome when performed at 30-34 103 or 35-37 104 weeks.…”