Study designs of evaluations included in the review
No inclusion criteria relating to the study design were specified.
Specific interventions included in the review
Studies that assessed uterine artery Doppler assessment were eligible for inclusion. Several types of Doppler imaging were used in the included studies: continuous-wave Doppler without visualising the vessel, pulse-wave Doppler after identification of the vessel using B-mode ultrasound, and colour flow imaging to identify the vessel followed by pulsed-wave Doppler. The ultrasound was carried out transvaginally in one study of colour pulsed-wave ultrasound; in all other studies it was carried out transabdominally. The threshold used to define a positive result varied between studies and included: a systolic-to-diastolic ratio greater than 2.18 or 2.7; a mean resistance index greater than 95th centile; a resistance index or mean resistance index greater than 0.55, greater than 0.57, greater than 0.58 or greater than 0.65, with or without the presence of notches; the presence of bilateral notches.
Reference standard test against which the new test was compared
Studies that assessed pre-eclampsia, foetal growth restriction (FGR) or perinatal death as reference standards were eligible for inclusion. The definitions of pre-eclampsia used by the studies were a blood-pressure of at least 140/90 mmHg and proteinuria greater than 150 or 300 mg/24 hours, or a rise in blood-pressure (systolic more than 30 mmHg and diastolic more than 25 mmHg) with proteinuria greater than 500 mg/24 hours. Definitions of FGR were below the 3rd, below the 5th or below the 10th centile.
Participants included in the review
Studies of unselected pregnant women were eligible for inclusion. The gestation periods ranged from 16 to 26 weeks.
Outcomes assessed in the review
The studies had to provide sufficient data to calculate measures of diagnostic accuracy to be eligible for inclusion. Likelihood ratios (LRs) were selected as the primary outcome. Data on screen-positive rates, prevalence, sensitivity, specificity, and positive and negative predictive values were also presented.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.