The Clinical Significance of Early Diastolic Notch of Uterine Artery Doppler Waveform Analysis in the Second Trimester

Introduction: The early diastolic notch of the uterine artery Doppler waveform analysis is thought to be the result of high resistance in blood flow. It is known to be associated with intrauterine growth restriction, pregnancy induced hypertension, and poor perinatal outcomes. But the clinical significance of early diastolic notch in the second trimester is not well known. Purpose: To evaluate the clinical significance of early diastolic notch of uterine artery Doppler waveform in the second trimester and to evaluate a possible role for notch index [NI] of uterine artery Doppler waveform in the second trimester to predict the persistence of early diastolic notch in the third trimester. Materials & Methods: Total 1708 pregnant women who had taken antenatal ultrasonographic examinations and uterine artery Doppler waveform analysis in the second and third trimester were groupped by the presence of early diastolic notch in the second and third trimester: group I [1553 cases] with no notch, group II [80 cases] with notch in the second trimester only, group III[36 cases] with notch in the third trimester only, and group IV [39 cases] with notch in both second and third trimester. The depth of early diastolic notch was assessed by NI, that was calculated as minimal velocity in early diastole divided by maximal velocity in diastole. Criteria of poor perinatal outcomes were as follows: cesarean section due to fetal distress, 5 minute Apgar score below 6, intrauterine growth restriction, neonatal intensive care unit admission, and perinatal death. The uterine artery Doppler waveform were measured at crossing area between uterine artery and iliac artery. Results: Ratio of poor perinatal outcomes of group Ⅰ, Ⅱ, Ⅲ, and Ⅳ were 10.6%, 15.0%, 47.2%, and 41.0%, respectively, and were significantly different between the groups [p＜0.05]. In the second trimester, the NI of cases with notch in the second trimester only [group Ⅱ, 0.84±0.16] showed significant difference from those of whom with notch in both second and third trimester [group IV, 0.80±0.19] [p＜0.05]. Conclusion: If there is an early diastolic notch of uterine artery velocity waveform in the second trimester, to evaluate the depth of early diastolic notch by NI could be useful in predicting whether early diastolic notch persists or not in the third trimester.restrictio