Predicting the risk of pre-eclampsia and a small-for-gestational-age infant by quantitative assessment of the diastolic notch in uterine artery flow velocity waveforms in unselected women

Objectives To develop a new quantitative index, the notch depth index (NDI) , to evaluate its association with the risk of pre-eclampsia and a small-fo r-gestational-age (SGA) infant and to compare its clinical usefulness with that of the uterine artery resistance index (RI) and the peak systolic to e arly diastolic velocity (A/C) ratio. Methods Uterine artery color Doppler ultrasound was performed in 288 consec utive healthy pregnant women at 20.2 +/- 2.0 (range 16.0-23.9) weeks of ges tation. The NDI represents the depth of the early diastolic notch divided b y the maximal diastolic velocity. Results Nine (3.1%) of the 288 women developed pre eclampsia and 18 women ( 6.3%) delivered an SGA infant. The NDI was associated with subsequent onset of pre-eclampsia. The optimal cutoff value for the NDI in predicting pre-e clampsia was 0.14, giving a sensitivity specificity and a positive predicti ve value (PPV) of 67, 92, and 22%, respectively The PPV of the NDI was the largest of the three indices evaluated (12% for the RI and 26% for the A/C ratio). The relative risk for pre-eclampsia in women with values equal to o r greater than the optimal cutoff values of the RI, A/C ratio and the NDI w as 9.7 (95% confidence interval, 2.5-3.7), 19.2 (4.2-91), and 19.2 (5.1-71) , respectively. The NDI of 0.14 improved the PPV of 18% determined by the p resence of notches in bilateral uterine arteries. The optimal cutoff value of 0.14 for the NDI in predicting an SGA infant yielded a higher PPV (22%) than those for the RI (9%) and AIC ratio Conclusions The NDI value in the second trimester is associated with the la ter onset of pre-eclampsia, and is clinically more useful In predicting pre -eclampsia than the two conventional indices.