Evaluation of the uterine artery resistance index by Doppler ultrasonography in pregnant women with chronic hypertension

Uterine placental bloodstream pressure can be measured by Doppler ultrasonography, which is a non-invasive technique. Uterine arteries velocimetry progressively decreases during the first and second trimesters in normal gestation due to trophoblastic invasion of musculoelastic membrane of uterine spiral arteries. The relationship between trophoblastic invasion and placental resistance index can be helpful in predicting gestation outcome intrauterine growth retardation in particular. The aim of this study was to measure the significance of uterine artery resistance index in predicting maternal and fetal complications in pregnant women with chronic hypertension.

Uterine artery velocimetry was investigated between 28 and 32 weeks after gestation in 67 chronic hypertensive pregnant women by means of colour Doppler sonograph. Resistance index (RI) was recorded and its relationship to the development of superimposed pre-eclampsia (SPE), pregnancy aggravated hypertension (PAH), and intrauterine growth retardation (IUGR) was surveyed. The obtained data was analysed employing SPSS using Fisher accurate test and P0.05 was considered as the significant level.

There were more pregnancy complications in 21 patients with abnormal RI compared with 46 patients with normal RI (SPE 43% vs.6.5%, PAH 24% vs. 4.3%, and IUGR 71% vs. 4.3%).

Uterine artery Doppler velocimetry helps to identify a subgroup of chronic hypertensive patients with a high frequency of pregnancy complications.