A cesarean scar (ectopic) pregnancy occurs when a pregnancy implants on a cesarean scar. This condition is an uncommon but potentially devastating occurrence. The incidence is increasing as cesarean deliveries become more common. Early recognition of the salient sonographic findings is critical because a delay can lead to increased maternal morbidity and mortality. Magnetic resonance imaging is a valuable troubleshooting tool when sonography is equivocal or inconclusive before therapy or intervention. Early diagnosis by sonography directs therapy and improves outcomes by allowing preservation of the uterus and future fertility. We review the imaging features, differential diagnosis, complications, and treatment of cesarean scar pregnancies in the first trimester.