A large intrauterine vascular lesion developing after the successful treatment of a cesarean scar pregnancy with methotrexate injection.

A cesarean scar pregnancy is a rare type of ectopic pregnancy. Induced abortion by local methotrexate (MTX) injection is an effective management approach. We describe a case in which a large intrauterine vascular lesion appeared after the sonographic-guided local injection of MTX, which successfully induced the abortion of the cesarean scar pregnancy. Although a cesarean scar pregnancy may be safely treated with a local MTX injection, close follow-up, including serum β-human chorionic gonadotropin level measurement and Doppler sonography, is needed because an intrauterine vascular lesion could develop even after a successfully induced abortion. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 46:222-226, 2018.