Does the ultrasound diagnosis of low-lying placenta in early pregnancy warrant a repeat scan?

A retrospective analysis of 732 consecutive deliveries at this hospital was undertaken to see if the early (15-20 weeks) pregnancy ultrasound placental localisation was of value, and whether the diagnosis of low-lying placenta warranted a repeat scan. The placental site was reported as normal in 413 pregnancies, as low-lying in 79 and was not recorded in 240. None of the women with a low-lying placenta developed placenta praevia. There were no significant differences in pregnancy outcome between those women with a low-lying placenta and those in whom it was normally situated. The ultrasound diagnosis of low-lying placenta between 15 and 20 weeks gestation does not warrant a repeat scan.