脉冲多普勒超声对胎儿不同妊周脐带及脑循环动态变化的研究

目的，探讨不同妊周胎儿脐血流及脑血流的变化规律。方法，对４２２例妊娠２１～４２周正常产妇，用脉冲多普勒超声测量其胎儿脐带动脉（ＵＡ）、大脑中动脉（ＭＣＡ）之ＲＩ（阻力指数）与ＰＩ（搏动指数）。结果与结论，ＲＩ与ＰＩ的变化高度一致（ｒ＝０．９７８）（ｐ＜０．００１）。ＵＡ两指数在妊娠２１周时最高，此后逐渐下降至足月（Ｐ＜０．００１）。ＭＣＡ两指数从２１周起先缓慢上升，２９周时达高峰，此后迅速下降至足月（ｐ＜０．００１）。ＵＡ的ＲＩ、ＰＩ与ＭＣＡ的ＲＩ、ＰＩ之比值，从妊娠２１周起迅速下降，２９～３４周间维持较低水平，以后缓慢上升，到妊娠足月时仍明显低于妊娠２１周时水平（Ｐ＜０．００１）。

Evaluation of Normal Fetal Umbilical and Cerebral Circulation at Different Gestational Weeks by Pulsed Doppler Method

The Normal fetal umbilical artery(UA)and middle cerebral artery(MCA)were examined by pulsed Doppler flow velocimetry in 422 cases of normal pregnancy ranged from 21st to 42nd gestational week,The resistance index (RI)and pulsatility index(PI)were calculated to find the changing regularity of fetal umbilical and cerebral blood flow at different gestational weeks.Results and conclusions:RI has the same developing regularity as that of PI(r=0.978)(p<0.00l)So far as the umbilical artery was concerned,RI and PI values were highest at the 21st gestational week,and declined gradually thereafter to term(P<0.001).RI and PI values of MCA increased gradually from the 21st week to the highest at the 29th week and declined slowly to term(P<0.001).UA/MCA ratios of RI and PI declined gradually from the 21st week,these after relatively stable within 29th-34th weeks.Yet,the ratios increased slowly to term but lower than that at the 21st week (P<0.001).