AbstractObjectiveTo evaluate our experience with the diagnosis and treatment of Cesarean scar pregnancy.MethodsDuring a 6‐year period, 12 cases of Cesarean scar pregnancy were diagnosed using transvaginal color Doppler sonography and treated conservatively to preserve fertility. Incidence, gestational age, sonographic findings, β‐human chorionic gonadotropin ( β‐hCG) levels, flow profiles of transvaginal color Doppler ultrasound, and methods of treatment were recorded.ResultsThe incidence of Cesarean scar pregnancy was 1:2216 and its rate was 6.1% in women with an ectopic pregnancy and at least one previous Cesarean section. Gestational age at diagnosis ranged from 5 + 0 to 12 + 4 weeks. The time interval from the last Cesarean section to the diagnosis of Cesarean scar pregnancy ranged from 6 months to 12 years. High‐velocity and low‐impedance subtrophoblastic flow (resistance index, 0.38) persisted until β‐hCG declined to normal. Patients were treated as follows: transvaginal ultrasound‐guided injection of methotrexate into the embryo or gestational sac (n = 3), transabdominal ultrasound‐guided injection of methotrexate (n = 2), transabdominal ultrasound‐guided injection of methotrexate followed by systemic methotrexate administration (n = 2), systemic methotrexate administration alone (n = 2), dilatation and curettage (n = 2), or local resection of the gestation mass (n = 1). Eleven of the 12 patients preserved their reproductive capacity; the remaining patient, treated by dilatation and curettage, underwent a hysterectomy because of profuse vaginal bleeding. The Cesarean scar mass regressed from 2 months to as long as 1 year after treatment. Uterine rupture occurred in one patient during the following pregnancy at 38 + 3 weeks' gestational age.ConclusionUltrasound‐guided methotrexate injection emerges as the treatment of choice to terminate Cesarean scar pregnancy. Surgical or invasive techniques, including dilatation and curettage are not recommended for Cesarean scar pregnancy due to high morbidity and poor prognosis. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.