Differential Diagnosis of Cesarean Scar Pregnancies and Other Pregnancies Implanted in the Lower Uterus by Ultrasound Parameters

PURPOSE: Cesarean scar pregnancy is an extremely rare type of ectopic pregnancy implanted in the myometrium at the site of a previous cesarean section scar. On the other hand, pregnancies are considered low implantations if they are identified in the lower third of the uterus without the sac implanted into the scar and have a better prognosis. Early diagnosis of both types of pregnancies can help avoid serious complications. This study is aimed at investigating the significance of transvaginal ultrasound in the differential diagnosis of cesarean scar pregnancies and pregnancies implanted in the lower uterus. METHODS: Ninety-three patients with an average age of 32.7 years (range, 24–43 years) were enrolled in this study, including 66 cesarean scar pregnancies and 27 other pregnancies implanted in the lower uterus, and they were examined by transvaginal ultrasound. RESULTS: We observed significant differences in the relationship between the cesarean sac and the scar, the source of the trophoblastic blood flow, and the thickness of the residual muscle between the cesarean scar pregnancy group and the lower uterus pregnancy group. We established the logistic model to improve the differential diagnosis of cesarean scar pregnancies and pregnancies implanted in the lower uterus. CONCLUSIONS: Transvaginal ultrasound is recommended in early pregnancy, especially for patients who have undergone a previous cesarean section delivery.