ABSTRACT
Introduction: The presence of a lowlying in the second trimester of pregnancy can be converted to an upper uterine segment placenta by the end of the third trimester. This phenomenon is important when a complete or marginal placenta previa is encountered in the second trimester of gestation because of the need to predict possible antepar-tum complications and mode of delivery. Aim:To examine the migration of placenta and the placental marginal sinus to predict the eventual route of delivery in low-lying placenta. Methodology:Women with a low-lying placenta with 30 weeks of gestation were included for study. The distance between the internal os and leading edge of the placen-ta was measured fortnightly using transvaginal ultrasonography until 36 weeks gestation. The relationship between the rate of placental migration, the presence of a placental marginal sinus and the eventual mode of delivery was investigated. Results:In the present study cesarean section rate was 60 % (39/65) in the slow migration group (0 –2.0 mm/week) group, six patients (6/35) in the fast (more than 2.0 mm/week) migration group underwent a cesare-an section (p < 0.01) because of other problems. The cesarean section rate was 75.9 % (22/29) in patients with a pla-cental marginal sinus, significantly greater than the rate of 11.3 % (8/71) in patients without a marginal sinus (p < 0.01). Conclusion:A decreased rate of placental migration until 36 weeks’ gestation and the presence of a placental marginal sinus were associated with subsequent cesarean delivery because of antepartum vaginal hemorrhage. These parameters may be useful for predicting the route of delivery in women with a lowlying placenta.