Objective: To study the efficacy of using Doppler ultrasound to measure blood flow within the uterine artery through the
determination of soluble fms-like tyrosine kinase-1 (sflt-1) levels, placenta growth factor (PlGF), and pregnancy-associated plasma protein-A (PAPP-A) in the plasma to predict the risk of preeclampsia in pregnant women over 35 years old at high risk of developing this condition.

Materials and Methods: Data were collected from pregnant women aged over 35 years who attended the antenatal clinic at the Department of Obstetrics and Gynecology, Thammasat University Hospital at gestational ages of 8 to 20 weeks. The patient information included age, parity, gestational age, past pregnancy history and the risk factors of preeclampsia development. All the participants had measured plasma levels of sflt-1, PlGF, and PAPP-A, followed by assessment through the ultrasound Doppler examination.

Results: Of a total of 296 participants, only 276 pregnant women were able to be tracked with enough data for analysis. There were 15 cases (5.43%) of pregnant women with preeclampsia, while the remaining 261 cases (94.57%) showed no complications of preeclampsia. In a comparison of average age, weight, body-mass index, parity and risk of preeclampsia history in the two groups, no statistically significant differences were found. There were also no statistically significant differences in gestational age at delivery or the birth weight of newborns. The ratio of blood-flow abnormalities in the uterine arteries of pregnant women who had preeclampsia was 26.67% (4/15 cases), which was higher than in the group that had no preeclampsia; the ratio for this latter group was found to be 16.48% (43/261 cases). However, there was no significant difference between the two groups (p = 0.31). The average ratio of sflt-1 to PlGF was higher in the pregnancies with preeclampsia, but there were no statistically significant differences (8.60+4.79, 8.09+5.24, p = 0.71). The multiple of median (MoM) of PAPP-A in pregnant women with preeclampsia was less than in those without preeclampsia, but no statistically significant differences were found. When all three factors were evaluated and appraised in statistical form for the prediction of preeclampsia, it was found that abnormalities of uterine artery blood flow increased the risk of preeclampsia by a factor of 1.78. A sflt-1-to-PlGF ratio greater than 14 increased the risk of preeclampsia by a factor of 2.54 and a PAPP-A less than 0.5 MoM increased the risk of preeclampsia by a factor of 2.5, respectively, while the prediction of total preeclampsia from all three factors was 64.62%.

Conclusion: In pregnant women over 35 years of age with these factors, there was a greater chance of preeclampsia. However, the combination of factors in predicting the likelihood of preeclampsia was not significant enough and was not worthwhile for use in clinical practice in this high-risk group.

Keywords: Preeclampsia, Prediction, sflt-1, PlGF, PAPP-A