Analysis of the Application Value and Association with Pregnancy Outcomes ofthe Abnormal Pulsatility Index of the Fetal Middle Cerebral Artery Diagnosed by Ultrasound

Objective This study aims to investigate the clinical significance and correlation with pregnancy outcomes of the abnormal pulsatility index (PI) of the fetal middle cerebral artery (MCA) as detected by ultrasonography. Methods A total of 41 cases with abnormal fetal MCA-PI (including five deaths) at the Maternal and Child Health Hospital of Haidian District, Beijing, were prospectively collected from July 2021 to July 2024, and 72 cases with normal fetal MCA-PI during the same period were selected as the control group. The differences in blood flow parameters between the two groups were compared, and the correlation between abnormal fetal MCA-PI and fetal pregnancy outcomes was analysed. Finally, the receiver operating characteristic curve was used to evaluate the predictive value of abnormal MCA-PI for adverse pregnancyoutcomes. Results Statistically significant differences were observed ( P < 0.05) in the comparative analysis of ultrasound parameters (MCA-PI, MCA-resistance index [RI], MCA-systolic-to-diastolic ratio [S/D], umbilical artery [UA]-PI, UA-RI, UA-S/D and cerebroplacental ratio [CPR]) between the abnormal MCA-PI group (n = 36) and the normal MCA-PI group (n = 72). Specifically, MCA-PI, MCA-RI and MCA-S/D were significantly lower and UA-PI, UA-RI and UA-S/D were elevated in the abnormal group relative to in the normal group. CPR in the abnormal group was significantly lower than that in the normal group. The normal and abnormal MCA-PI groups showed statistically significant differences ( P < 0.05) in clinical parameters (neonatal birth weight, Apgar score, umbilical cord hypercoiling, placental thickening, eclampsia, fetal distress, fetal growth restriction and preterm birth) but not in the incidence of UA occlusion ( P > 0.05). Compared with the normal group, the abnormal MCA-PI group had a significantly higher risk of adverse pregnancy outcomes, with the risk of preterm birth being 5.6 times higher. The proportion of neonates with low birth weight in the abnormal MCA-PIgroup reached 44.4%. Amongst the 41 cases of fetuses with abnormal MCA-PI, statistically significant differences were observed in neonatal birth weight and Apgar scores across different pregnancy outcomes ( P < 0.05), whereas no significant difference was found in the gestational week at diagnosis ( P > 0.05). Neonatal birth weight and Apgar scores in the abnormal MCA-PI group were significantly lower than those in the normal group, with a trend towards early gestational weeks at ultrasound diagnosis. The area under the curve for predicting adverse pregnancy outcomes using abnormal MCA-PI was 0.743, with a sensitivity of 86. 1%. Conclusions Abnormal MCA-PI is a sensitive and effective indicator for evaluating fetal blood oxygen supply and has a high predictive value for adverse pregnancy outcomes.