Photo Credit: Henadzi Pechan

Second-trimester UtA-PI or the ratio of second-to-first-trimester UtA-PI may help women at high risk for preeclampsia who don’t respond to aspirin prophylaxis.

Recently, prophylactic low-dose aspirin has gained acceptance for pregnant women at high risk for preeclampsia. However, the benefits of aspirin may not be evident in certain groups of pregnant women, and the etiology remains unknown. Therefore, identifying high-risk women not responding to aspirin prophylaxis is clinically important.

Chia-Chen Lee, MD, and colleagues conducted a retrospective cohort study of 206 women identified as high-risk for preeclampsia through first-trimester screening and prescribed aspirin prophylaxis. The researchers compared maternal characteristics, medical history, biochemical markers, and uterine Doppler indices between women with preeclampsia (n=35) and a control group (n=171).

The primary endpoint was preeclampsia diagnosed by the new onset of hypertension accompanied by proteinuria after 20 weeks of gestation in previously normotensive women. The findings were published in the Taiwanese Journal of Obstetrics & Gynecology.

Women with preeclampsia had significantly higher rates of chronic hypertension compared with the control group (54.3% vs 8.2%, respectively; P<0.0001). Additionally, the preeclampsia group exhibited higher rates of first-trimester mean arterial pressure (MAP; 109.6 mmHg vs 95.4 mmHg) and BMI (27.6 vs 24.9).

In the second trimester, the researchers also reported significantly elevated MAP in the preeclampsia group (103.3±15.2 mmHg) compared with the control group (89.7±10.6 mmHg; P< 0.0001). The mean uterine artery pulsatility index (UtA-PI) was also significantly higher in the preeclampsia group (1.39±0.60 vs 1.05±0.33, respectively; P<0.0001).

Receiver-operating characteristic curve analysis identified an optimal second-trimester UtA-PI cut-off of 1.36 for predicting preeclampsia, with sensitivity of 49% and specificity of 87.1%. The researchers noted that the ratio of the mean UtA-PI in the first and second trimesters emerged as an important indicator for the detection of preeclampsia compared with relying solely on the mean UtA-PI value in the second trimester (AUC, 0.777 vs 0.683). Additionally, when using the ratio of second-to-first-trimester mean UtA-PI with a cut-off value of 0.77, the sensitivity and specificity were 60% and 90.6%, respectively.

Dr. Lee and coauthors wrote that evaluating second-trimester UtA-PI or the ratio of second-to-first-trimester UtA-PI may be a promising tool for identifying high-risk women who do not respond to aspirin prophylaxis.

“The findings suggest that women at a high risk for preeclampsia, undergoing aspirin prophylaxis with an elevated second-trimester UtA-PI or an increased second-to-first-trimester UtA-PI, require additional clinical investigation and care.”