We screened 225 symptom-free pregnant women at increased risk for ectopic pregnancy with transvaginal sonography and human chorionic gonadotropin (hCG) assays. Among 55 (24.4%), who proved to have an ectopic pregnancy, 46 (84%) cases were diagnosed at the initial screening at a median of 37 days of gestation, and the rest at repeated scans. The false-positive rate was 1.2%. Early diagnosis prevented tubal rupture, substantial haemorrhage, and the need for emergency care, allowing elective treatment. Such early surveillance reduced the risk of complications and facilitated treatment, and should be offered to at-risk women.