Value of Third Trimester Uterine Artery Doppler in High-risk Pregnancies for Prediction of Adverse Perinatal Outcome

Abstract

Objective: To determine the usefulness of uterine artery Doppler in third trimester high risk pregnancies for prediction of adverse perinatal outcome. Methods: This prospective study was performed in a tertiary care centre in the West Coast of India. Inclusion criteria for the study were patients admitted with hypertensive complications in pregnancy, fetal growth restriction and women with previous recurrent pregnancy loss with no living children. Both uterine and umbilical artery Doppler were performed using Doppler ultrasound LOGIQ700 (3.5 MHz) with a high pass filter. Uterine artery Doppler parameters recorded were pulsatility index (PI > 1.2 considered abnormal) and presence of early diastolic notch. Uterine artery score (UAS) was calculated from the Doppler parameters as described by Hernandez et al and a score ≥2 was considered abnormal. Umbilical artery Doppler was considered abnormal when PI > 2 SD for gestational age or absence/reversal of end diastolic flow. Repeat Doppler was done after one week if the patient did not deliver. The last Doppler findings closer to delivery were correlated with perinatal outcome. Results: There were sixty cases of high risk pregnancy mainly consisting of Preeclampsia and fetal growth restriction included in this study. The mean gestational age was 34 weeks with a range of 28-37 weeks. Forty percent of pregnancies were below 34 weeks of gestation. Abnormal UAS was noted in 72% of the study group while umbilical artery Doppler was abnormal in only 35%. Almost 33% had abnormal Doppler findings in both vessels. All the five perinatal deaths and high rate of perinatal morbidity was observed when both uterine and umbilical artery Dopplers were abnormal. Over all perinatal mortality was 83/1000 live births. Neonatal morbidity was significant with almost 50% requiring neonatal intensive care unit (NICU) admissions. Perinatal morbidity parameters such as birth weight below 2000 gm, gestational age <34 weeks and NICU admission was significantly high in 23 women who had abnormal UAS with normal umbilical artery Doppler. There were 36 patients who were beyond 34 weeks of gestation. In this subgroup abnormal UAS was noted in 18 (50%) while only 6 (16.7%) had abnormal umbilical artery Doppler. Small for gestational age babies, neonatal morbidity and cesarean delivery was three fold higher in those with abnormal UAS and normal umbilical artery Doppler in this group. Conclusion: Abnormal uterine artery Doppler in the third trimester is a reliable predictor of adverse perinatal outcome in high risk pregnancies with preeclampsia and fetal growth restriction. Uterine artery Doppler scoring system makes interpretation simple for clinical practice. Perinatal outcome was poor when both uterine and umbilical artery Doppler were abnormal. We observed less neonatal morbidity in preeclampsia and fetal growth restriction when uterine artery Doppler was normal in 3rd trimester. This important fact can be reassuring. In pregnancies beyond 34 weeks abnormal uterine artery Doppler was a better predictor of adverse outcome than umbilical artery Doppler. Thus inclusion of uterine artery Doppler along with umbilical artery Doppler in high risk pregnancies in third trimester will improve fetal surveillance.