Reference values of fetal peak systolic blood flow velocity in the middle cerebral artery at 19-40 weeks of gestation

Objectives The objectives of this prospective study were (i) to establish n ew reference values of peak systolic blood flow velocity measurement in the fetal middle cerebral artery (MCA-PSV) following validated methodological guidelines and (ii) to develop a method to calculate Z-scores of MCA-PSV. Patients and Methods Cross-sectional data were obtained from 331 pregnant w omen between 19 and 40 weeks' gestation. Reference ranges for MCA-PSV were constructed and for each measurement linear regression models were fitted s eparately to the mean and standard deviations (SD) as a function of gestati onal age. An application to calculate Z-scores was developed. A comparison was made between the reference ranges produced in our study and those of a previous one. Results A new chart, table of centiles and regression equations of MCA-PSV are presented. Comparison of our reference ranges with ones produced in a p revious study showed similar 5(th) centile values. However, the values for the 50(th) and 95(th) centiles between 19 and 28 gestational weeks were low er in our study. Conclusions We have constructed reference ranges for MCA- PSV which, becaus e they are derived from a larger number of examinations in the 15-20-week p eriod and because the methodological flaws of the previously published stud y have been eliminated, we consider to be more accurate and therefore more useful for clinical practice.