J. Aquilina et al., Comprehensive analysis of uterine artery flow velocity waveforms for the prediction of pre-eclampsia, ULTRASOUN O, 16(2), 2000, pp. 163-170
Objectives To evaluate the performance of velocimetric indices of uterine a
rtery flow velocity waveforms (FVW's) at 20 weeks' gestation, alone or in c
ombination with qualitative analysis, and establish the optimal screening m
ethod for the prediction of pre-eclampsia.
Methods A total of 614 primiparous women had color flow/pulsed Doppler (CFP
D) imaging of both uterine arteries at 20 weeks gestation. Receiver operato
r characteristic (ROC) curves were created for the systolic/end-diastolic (
A/B) ratio, resistance index (RI) and systolic/ early diastolic (A/C) ratio
for placental and non-placental uterine arteries, individually or in combi
nation with the presence of unilateral or bilateral notches. Based on data
from ROC curves, the sensitivity of each method was compared with the false
-positive rate set at 17 and 11%.
Results The highest sensitivity (88%) and specificity of (83%) was obtained
using bilateral notches/mean RI greater than or equal to 0.55 (50th centil
e) and unilateral notches/mean RI greater than or equal to 0.65 (80th centi
le). When the false-positive rate was set at 17%, the inclusion of bilatera
l notches significantly improved the sensitivity of RI (P <0.001), placenta
l RI (P <0.02), placental A/C ratio (P < 0.05), mean A/C ratio (P < 0.01) a
nd mean A/B ratio (P < 0.05). Bilateral notches/mean RI or A/B cut-offs wer
e also superior to the persistence ofa notch in either artery combined with
RI (P < 0.01) or A/B ratio (P < 0.05). When the false-positive rate was se
t at 11%, the inclusion of bilateral notches did not improve the sensitivit
y of the A/C (P =1.00) or A/B ratio (P > 0.10). Placental velocimetric indi
ces performed better than mean indices but the differences in sensitivity a
t the set false-positive rates were not statistically significant.
Conclusion At 20 weeks' gestation, bilateral notches with mean RI cut-offs
is the best screening method if further screening later in pregnancy is pro
posed. The AIC ratio is complementary to bilateral notches when the false-p
ositive rate is set at 17% and an effective quantitative substitute when th
e false-positive rate is set at 11%.