Is Middle Cerebral Artery Doppler a Reliable Tool for Fetal Monitoring? A Prospective Observational Study on Intra and Inter-Observer Variability.

Purpose: Evaluation of intra- and inter-observer variability of middle cerebral artery (MCA) pulsatility index (PI) in pregnancies complicated by fetal growth restriction (FGR) compared to normally grown controls and literature review.

Methods: Prospective observational cross-sectional study. Singleton pregnancies between 26 and 40 weeks were included and divided into two groups based on fetal growth: fetal growth restricted and normally grown fetuses. Fetal growth restricted fetuses were divided into early and late FGR. Intra-and inter-observer variability were assessed by Intraclass Correlation Coefficient (ICC) and interpreted following the TRUST criteria and GRRAS guidelines.

Results: One hundred and fifty patients were included in the study. Forty-eight cases were complicated by FGR: 27 early-onset and 21 late-onset. 13/48 (27%) showed middle cerebral artery redistribution. Intra and interobserver reproducibility were "poor" in the appropriate for gestational age (AGA) fetuses. In the FGR group, the intraobserver reproducibility was "moderate" and interobserver reproducibility was "moderate/poor". Intraobserver reproducibility was "good" in early FGR and "moderate" in late FGR cases, while interobserver reproducibility was "moderate" in early FGR and "poor" in late FGR cases.

Conclusion: MCA PI Doppler repeatability is superior in FGR fetuses compared to AGA fetuses. MCA pulsatility index can be used with confidence in FGR, especially if early onset.