Placenta accreta and uterine arteriovenous malformation following medically treated missed abortion in patient with undiagnosed cesarean scar pregnancy.

Cesarean scar pregnancy (CSP) is a rare condition, accounting for 6% of ectopic pregnancies, with a rising incidence. If not diagnosed early, it may lead to severe complications such as hemorrhage, need for surgery, placenta accreta, and arteriovenous malformation (AVM). Treatment consists of expectant management, medical, or surgical regiments. A 31-year-old woman (G3P2) with one previous cesarean section presented for early pregnancy evaluation. Ultrasound initially showed an intrauterine pregnancy, but follow-up confirmed a missed abortion, and mifepristone/misoprostol regimen was initiated. At follow-up, persistent tissue at the cesarean scar raised suspicion of scar pregnancy. Declining human chorionic gonadotropin levels were noted, and expectant management implemented. Increased bleeding led to ultrasound and magnetic resonance imaging, revealing a 10 cm tumor suspicious of AVM. Fertility-preserving surgery with laparoscopic 'niche' resection technique was pursued, but hysterectomy was ultimately required. Histopathological examination showed placenta accreta. Early diagnosis and management of CSP are essential to reduce serious complications.