A study for predicting toxemia of pregnancy by the diastolic notch in pulsed Doppler flow velocity waveforms of the uterine arteries--quantitative analysis of the diastolic notch as uterine arterial index (UTAI)

To investigate the ability of measurement of the diastolic notch in Doppler flow velocimetry to predict development of toxemia of pregnancy, analysis of uteroplacental and fetal blood flow waveforms was performed. The waveforms were analyzed by calculating the resistance index (RI) and the pulsatility index (PI) and were investigated whether diastolic notches existed or not. In the prospective study, the uterine arterial index (UTAI; an index introduced to evaluate the degree of diastolic notch quantitatively) was also calculated. RETROSPECTIVE STUDY: The waveforms in the uterine arteries, the umbilical artery and the fetal vessel (inferior vena cava, descending aorta and middle cerebral artery) were measured in 153 pregnant women. PROSPECTIVE STUDY: Uterine artery velocimetry was performed at 16-23 weeks' gestation in 387 pregnant women. RESULT 1: Subjects with a diastolic notch had significantly higher rates of development of toxemia of pregnancy. Indexes of the fetal blood flow waveforms had no significant correlations with the development of toxemia of pregnancy. RESULT 2: UTAI showed an equivalently high negative predictive value (98.1%) and higher positive predictive value (17.6%) than RI (98.2%, 10.2% respectively) and PI (98.7%, 12.7% respectively). CONCLUSION: UTAI measurement was more useful for predicting toxemia of pregnancy than RI or PI.