Value Of Ultrasonic Measurement Of Fetal Mesencephalon Diameter In Prenatal Examination

Objective To establish a reference chart of fetal mesencephalon anteroposteriorand transverse diameter via ultrasonographic cross sectional imaging at differentmaternal gestational ages, compare measurement of fetal mesencephalonanteroposterior and transverse diameter of fetuses associated with central nervoussystem abnormality and95%confidence interval of normal fetuses at the samematernal gestational ages, to evaluate the significance of measurement of fetalmesencephalon anteroposterior and transverse diameter in prenatal examination.Methods A total of931fetuses of pregnant women receiving hospital care fromJanuary2013to October2014at the Department of Obstetrics and Gynecology, JilinUniversity Hospital, were included in this study.31fetuses associated with centralnervous system abnormalities were assigned to the observation group. The controlgroup consisted of900randomly selected fetuses of pregnant women. Themesencephalon anteroposterior diameter（MAD） and mesencephalon transversediameter （MTD） were measured on ultrasonographic images showing across-sectional view of the fetal head. Fetal MAD and MTD measured in controlfetuses at maternal GA20-40weeks were used to calculated the5th,50th, and95thpercentiles for each parameter at different maternal GA during normal development.The association between mesencephalon measurement and maternal GA wasevaluated by linear regression analysis. Statistical analyses were performed using theSPSS19.0software.Results Fetal mesencephalon anteroposterior diameter and mesencephalontransverse diameter were measured on cross-sectional brain ultrasonographic imagesof all631fetuses. In the control group, fetal Fetal mesencephalon anteroposteriordiameter and mesencephalon transverse diameter showed an incremental linearcorrelation with maternal GA, the equation of mesencephalon anteroposteriordiameter is Y=0.340X-0.272, R2=0.772, P<0.05, the equation of mesecephalontransverse diameter is Y=0.522X+0.834, R2=0.834, P<0.05.Within31cases of fetuses with CNS abnormality in observation group, included3cases of fetal corpus callosum dysplasia, one of which MAD and MTD are less than95%confidence interval in the control group of the same GA; one case of fetalholoprosencephaly, which MAD and MTD were less than95%confidence interval inthe control group; one case of Galen Venous aneurysm, the MAD and MTD were located in95%confidence interval of the control group of the same;5cases of Dandy-Walker syndrome,1case of typical Dandy-Walker syndrome, MTD was less than95%confidence interval in the control group,3cases of variant Dandy-Walkersyndrome, MAD and MTD of one case which is with omphalocele was less than95%confidence interval in the control group,1case of simple posterior fossa poolbroadened, MAD and MTD were less than95%confidence interval in the controlgroup;16cases of lateral ventricle broadening, MAD of3cases were less than95%confidence interval in the control group of the same GA, MTD of2cases were lessthan95%confidence interval of the same GA; one case of porencephaly, MAD andMTD were less than95%confidence interval;1cases of intracranial hemorrhage,MAD and MTD were within95%confidence interval of the same GA, but strongecho of hemorrhage can be found on the cross section.3cases of intracranial cysticplaceholder, MAD and MTD of1case were less than95%confidence interval at thatGA;1case of encephalocele, MTD was smaller than95%confidence interval of thesame GA.Conclusion The diameter of the fetal mesencephalon can easily and reproduciblybe measured via ultrasonographic cross sectional imaging. This study providesreference nomograms for the diameter of the fetal mesencephalon at variousgestational ages that may be helpful when evaluating fetal central nervous systemdevelopment.