Background many placenta previa cases diagnosed at mid-trimester resolve later in pregnancy,
hence comes the importance of searching for predictive factors for placenta previa resolution.
Uterine artery velocimetry parameters were suggested to play this role.
Aim to evaluate the predictive role of uterine artery Doppler velocimetry at mid-trimester of
gestation for placenta previa resolution at end of pregnancy third trimester.
Methods prospective cohort study was carried upon 200 pregnant women. Placenta-cervix os
distance was measured both at 22–24 weeks and after 36 weeks of gestation. Uterine artery
Doppler velocimetry parameters were measured at 22–24 weeks of gestation.
Results Subjects were assigned to control group (n=139), resolved group (n=36), and placenta
previa group (n=25) according to their diagnosis of placenta previa at mid-term and third trimester
end. Differences in uterine artery Doppler velocimetry parameters (S/D ratio, PI, and RI) between
different studied groups were used for analysis. Mean S/D ratio, PI, and RI of uterine arteries in
placenta previa group were significantly lower than in both control and resolved groups. No
differences were observed between control group and resolved group. Areas under the ROC curve
were 0.895, 0.898, and 0.908 for the means of S/D ratio, PI, and RI, respectively (P value < 0.001).
Conclusion uterine artery Doppler velocimetry parameters at mid-trimester are much lower in
patients with persistent placenta previa than in control and resolved groups and have potential to
predict placenta previa resolution.