A New Perspective to Evaluate Doppler Vascular Impedance in Hypertensive Disorders Complicating Pregnancy: Multilevel Modeling Established in a Case Control Study

Ting Yuan¹, Ting Zhang¹, Chao Li², Zhen Han^1*

¹Department of Obstetrics & Gynecology, First Affiliated Hospital of Xi’an Jiaotong University College of Medicine, Xi’an, China.
²Department of Public Health, Xi’an Jiaotong University College of Medicine, Xi’an, China.

DOI: 10.4236/ojog.2015.56051                

Abstract

Background: There have been researches on the evaluation of Doppler vascular impedance in hypertensive disorders complicating pregnancy (HDCP). With respect to the method of analysis used and the conclusions drawn in previous studies, different vessels were usually viewed separately and independently. This study was designed to evaluate Doppler vascular impedance changes in HDCP from a new perspective, with original thought and insight into an ordinary issue. Methods: 273 pregnant women (110 hypertensive pregnancies and 163 normotensive pregnancies) were randomly included in a grouping case-control study conducted from February 10, 2011 to April 30, 2013. All women in the study underwent Doppler measurements of six different vessels including the umbilical artery, the uterine arteries, the placental bed spiral artery, the fetal middle cerebral artery and the fetal renal artery. Doppler vascular impedance was presented as pulsatility index (PI), resistance index (RI), and systolic and diastolic ratio (S/D). Doppler changes in the hypertensive and normotensive groups were assessed by the multilevel modeling approach with univariate and multivariate-adjusted analyses. Results: According to multilevel modeling approach with multivariate-adjusted analysis, a relatively average evaluation on Doppler vascular impedance was provided. Hypertension was significantly associated with positive effects on PI, RI and S/D values (coefficients were 0.10, 0.03 and 0.08, respectively; 95% CIs were 0.06 - 0.14, 0.02 - 0.04 and 0.04 - 0.11, respectively; P values were all less than 0.001) in comparison with normotensive group. Conclusion: According to an overall evaluation, Doppler vascular impedance in hypertensive disorders complicating pregnancy was higher than in normotensive pregnancy. The novel thought and approach applied in this research may bring about inspirations for better understanding and assessment of the disease.

Keywords

Pregnancy, Doppler, Vascular Impedance, Multilevel Modeling

Conflicts of Interest

The authors declare no conflicts of interest.

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