The role of color Doppler imaging of the uterine arteries at 20 weeks' gestation in stratifying antenatal care.

OBJECTIVE

To determine the value of one-stop color Doppler imaging of the uterine arteries at the time of the 20-week anomaly scan, to select women at risk of developing pre-eclampsia and intrauterine growth restriction (IUGR).

PATIENTS AND METHODS

A total of 1022 unselected women had color Doppler imaging of both uterine arteries at the time of their dating/anomaly scan (19-21 weeks' gestation). The presence or absence of notching of the flow velocity waveform (FVW) was noted, and the resistance index (RI) was measured. The main outcome measures were pre-eclampsia, birth weight, placental abruption and stillbirth.

RESULTS

The outcome in 946 women (92.6%) was available for analysis. Of these, 216 (23%) had abnormal uterine artery Doppler studies, 117 (12.4%) with bilateral (right and left FVW) notches; 21 (2.2%) women developed pre-eclampsia, and 57 (6.0%) neonates were small for gestational age (SGA; < 5th centile), at birth. For women with bilateral notches the odds ratio (OR) for developing pre-eclampsia was 12.8 (95% confidence interval (CI) 5.3-30.8), and 52.6 (95% CI 6.4-430.1) for pre-eclampsia requiring delivery before 37 weeks' gestation. If the uterine artery Doppler studies were normal, the odds ratio for developing pre-eclampsia was 0.11 (95% CI 0.04-0.28), and 0.3 (95% CI 0.17-0.51) for the delivery of an SGA baby less than the 5th centile. In women with bilateral notches with mean RI greater than 0.55, the positive predictive value for the main outcome measures was 46%.

CONCLUSION

Women with normal uterine artery color/pulsed Doppler studies at 20 weeks' gestation constitute a group that have a low risk of developing obstetric complications related to uteroplacental insufficiency. Women with high resistance in both uterine arteries (bilateral notches) have an increased risk of the subsequent development of such complications, in particular those requiring delivery before term. The addition of color Doppler imaging of the uterine arteries at the time of the routine 20-week dating/anomaly scan may be of use in determining the type and level of antenatal care that is offered to women.