Salim I, Staines-Urias E, Mathewlynn S, et al. - In view of recent evidence indicating that a third trimester scan might aid in eliminating undiagnosed breech, researchers here evaluated how introduction of a routine 36-week scan affects the incidence of breech presentation and of undiagnosed breech presentation. In this population-based cohort study of pregnant women in a single unit covering Oxfordshire, United Kingdom, they assessed breech outcomes of 278,250 term births before and after the introduction of a third trimester screening ultrasound, which raised the proportion of pregnancies screened from 39% to 99%. There was a substantial fall in the incidence of undiagnosed breech presentation, however, 1 in 20 breech babies at term were still not diagnosed until labor. No reduction in the incidence of breech presentation at term was evident, albeit from an already low incidence. Observations overall suggest that the introduction of a third trimester screening scan into a maternity service does not prevent the occasional need for skills at breech birth, which themselves need experience.