Non-invasive diagnosis of fetal anemia: Multicentric nationwide input for a worldwide output

Abstract

PurposeTo perform a nationwide multicentric validatation of the nomogram of fetal middle cerebral artery peak systolic velocity (MCA-PSV); previously constructed by us and to compare and contrast it with similar studies in the world for an effective output. Materials and methodsFetal MCA-PSV was measured in normal 1015 pregnant women attending the antenatal ultrasound clinic at least once between 12 and 40 weeks of gestation (35 patients per week of gestation), at this institute and a nomogram was constructed. MCA-PSV in 30 patients each at 12, 24 and 36 weeks of gestation (GA) were measured at multiple centers [other institutes by different observers] in this nation. Their mean values were compared with the mean values mentioned in the nomogram prepared by us. Similarly the linear correlation diagrams as well as the regression equations of this large local study were compared with those from other worldwide published studies. Statistical analysis was done using the SPSS 12 software. ResultsA nationwide comparison of the mean and standard deviation (SD) values of MCA-PSV at 12, 24 and 36 weeks of gestation calculated at 95% confidence interval, in our study with studies from different other centers, using ANOVA the calculated F value was far too high than the table value. So, null hypothesis that the nomogram previously prepared by us at this center can be comfortably followed at other centers in this nation is rejected. Comparative analysis of linear correlation between GA (weeks) and MCA-PSV (cm/s) in our study and other studies also displayed a disparity. ConclusionsA significant difference was found between local study and multicentric nation wide studies, as well as between local values and worldwide values. A multicentric nationwide input for a worldwide output thus enabled us not only to construct and compare normal local reference range of fetal MCA-PSV but also to validate it effectively and to realize its limitations. Hence it is time to say goodbye to the “One Size Fits All Theory” of fetal MCA-PSV and to welcome efforts to scientifically construct regional reference range all over the world.