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Determination of Doppler Middle Cerebral Artery Waveform Indices in Normal 20 – 40 Weeks Pregnancies

Author(s): S. Vahdinia | M. K. Tarzamni | F. Gatre Samani

Journal: Iranian Journal of Radiology
ISSN 1735-1065

Volume: 5;
Issue: S1;
Start page: 54;
Date: 2008;
Original page

Background/Objective: The aim of prenatal evaluation is to prevent fetal death. One of the main methods of evaluation of fetus health before delivery is Doppler flow velocity waveform analysis of fetus vessels. Increasing of resistance in fetal circulatory system causes the preferential shunt of blood flow from non-critical organs toward critical organs such as brain. The increase in brain blood flow leads to reduction of brain vessels resistance and results in changes of fetal cerebral arteries Doppler flow velocity indices. Evaluation of Doppler wave of middle cerebral artery can predict most of the at risk fetuses in high-risk pregnancies."nIn this study we tried to obtain normal value (and their changes across the progress of pregnancy) of Doppler flow velocity indices (PI, RI, S/D ratio and PSV) of middle cerebral artery in 20 - 40 weeks normal pregnancies in an Iranian population and evaluate the effect of fetus heart rate according to the above mentioned indices."nPatients and Methods: In this cross section study, 400 pregnant women with normal pregnancies and gestational age between 20 to 40 weeks were studied about middle cerebral artery Doppler examination. Mothers with preeclampsia, diabetes mellitus, hypertension, abnormal uterine bleeding, induction ovulation, multifetal pregnancy, major fetal anomalies, history of LD or any other OCP usage and intra uterine growth retardation were excluded from the study. All cases were evaluated by gray scale ultrasonography initially and then a Doppler study of middle cerebral artery was done."nResults: According to the results of this study, with progression of pregnancy PI, RI, S/D ratio values decrease and PSV value increases in middle cerebral artery. These changes were statistically significant and were more characteristic during late weeks of pregnancy. In addition, mean fetal heart rate had been significantly reduced with pregnancy progression."nConclusion: Values of RI, PI, S/D ratio and PSV indices were somewhat similar to other studies. Nevertheless, it seems that racial factors may cause some changes in desired indices normograms. Usage of specific normograms for different geographical regions can yield more confidence level for examination of fetus by mean of middle cerebral artery implementing color flow Doppler.
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