Three dimensional transvaginal ultrasonography: Can it improve management in cases of laterally located minor placenta previa?

ObjectiveTo improve management of cases of minor placenta previa that is located laterally by more accurate measurement of edge-to-os distance using 3D transvaginal ultrasonography.MethodsFifty cases of laterally located minor placenta previa in the third trimester were included in the study. 2D TVS was done for all cases to measure the edge-to-os distance, then a 3D volume was taken for all cases and manipulated to get the coronal plane of the cervical canal, and the distance between the lateral edge of the internal os and the placental edge was measured and compared to 2D distances in each case.ResultsIn 46/50 cases (92%), distances measured by 3D ultrasound were less than those measured by 2D ultrasound. The decision about mode of delivery was changed from attempt of vaginal delivery to cesarean delivery in 39/50 cases (78%), as 2D distances that were ⩾20 mm were actually <20 mm by 3D examination in these cases.ConclusionsIn most cases of laterally located minor placenta previa, edge-to-os distances measured by 3D TVS were shorter than those measured by 2D TVS, thus changing management options in a considerable number of cases from attempt of vaginal delivery to elective cesarean section.