Late-diagnosed cesarean scar pregnancy resulting in unexpected placenta accreta spectrum necessitating hysterectomy.

Cesarean scar pregnancy (CSP) is a rare complication involving the implantation of the gestational sac in a cesarean delivery scar. The authors report a case of unexpected placenta accreta spectrum (PAS) caused by late diagnosed CSP, necessitating emergent hysterectomy. A 28-year-old Japanese woman with two previous cesarean deliveries presented to our hospital at 11 weeks of gestation with abnormal transvaginal ultrasound findings obtained at another hospital;however, transabdominal ultrasound revealed that the fetus was already present in the uterine cavity at this time. At 28 weeks, there was no evidence of placenta previa. The woman developed preeclampsia at 29 weeks, and a cesarean section was conducted. Intraoperative findings confirmed PAS, and hysterectomy was conducted immediately.