417: Cerebro-placental ratio at third trimester screening as a predictor of adverse perinatal outcome


      The aim of this study is to determine the value of cerebroplacental ratio (CPR) at routine third trimester scan in an unselected obstetric population to predict adverse perinatal outcome.

      Study Design

      A quasi-experimental study was carried out including 5071 consecutive routine third trimester ultrasound scans (32+0-34+6 weeks) performed in a University Hospital. The CPR was calculated in unselected patients according to the explorer’s criteria, as a ratio of the middle cerebral artery to the umbilical artery pulsatility indices. CPR below the 5 centile by gestational age was define as abnormal. Exclusion criteria were major congenital anomalies, aneuploidy and multiple pregnancy. Ultrasound, clinical and perinatal data were collected from computerized clinical databases. Statistical analysis was performed with SPSS 20


      CPR was assessed in 3325 pregnancies (65.6%). Those patients with abnormal CPR presented a statistically significant increase in preeclampsia (7.4% vs. 1.4% vs 1.3%, p = 0.024), prematurity (37% vs. 6.4% vs 8.4%, p = 0.001), born small for gestational age (SGA) (48.1% vs. 11.8% vs 7.2%, p = 0.001), Apgar 5 minutes <7 (3.7% vs. 0.5% vs 1.1%, p = 0.009), neonatal admission (25.9% vs. 4.5% vs 4.5%, p = 0.001) and cesarean section rate (48.1% vs. 20.2% vs 21.9%, p = 0.001), compared with normal or not performed. (Table 1) No differences were found among sociodemographic variables between groups.
      The cohort in which the CPR was evaluated, whether normal or pathological, had a decrease in the prematurity rate (6.7% vs. 8.4%, p = 0.028); Apgar test 5 minutes <7 (0.5% vs. 1.1%, p = 0.020) and perinatal mortality (0.1% vs. 0.5%, p = 0.011) compared with patients in whom CPR was not evaluated. (Table 2) Abnormal CPR was a best predictor of prematurity, Apgar 5 minutes <7, cesarean sections and neonatal admission than the isolated evaluation of the middle cerebral artery (MCAPI) or the umbilical artery (UAPI).


      Routine third trimester cerebroplacental ratio screening is associated with a decrease in the rate of prematurity, SGA, Apgar 5 minutes <7 and perinatal mortality. These results should be confirm by randomized clinical trials.
      Figure thumbnail fx1
      Figure thumbnail fx2