Obstetricians may unexpectedly encounter placenta accreta in the third stage of labor during vaginal delivery. An inadvertent attempt to remove a retained placenta due to accreta at delivery may lead to uterine inversion or devastating postpartum hemorrhage (PPH) [1]. The risk factors of placenta accreta include but are not limited to previous uterine surgery and prior endometrial injuries secondary to inflammation, curettage or electric cauterization [2]. It remains a great challenge for obstetricians to suspect and identify placenta accreta occurring in a primigravida who has a lack of risk factors. A 29-year-old primigravid woman suffered from a retained placenta, which was trapped in the cervix for 50 minutes after vaginal delivery. The patient had no previous histories of uterine surgery or infection. The signs of expulsion and elongation of the umbilical cord were noticed and the front part of placenta was palpable at the cervical os and visible from the vagina. A transabdominal sonography performed 1 hour after vaginal delivery revealed a very thin posterior uterine wall at the placental implantation site and an active low-resistance intraplacental flow, indicating an active functional placenta accreta with incomplete separation. Transcatheter arterial embolization (TAE) of the bilateral uterine arteries using gelfoam, which was performed 3 hours after delivery, prevented acute intrauterine bleeding. Three days after the application of TAE, significant amounts of blood accumulated in the uterine cavity proximal to the placenta that was confined to the excessively distended lower segment of the uterus (Fig. 1A). An obscured interface between the placenta and the very thin posterior uterine wall was clearly shown on computed tomography scan (Fig. 1B). Without anesthesia, ring forceps were used to remove most of the placenta except for the residual part of placenta accreta, which