Missing decidual Doppler signals as a new diagnostic criterion for placenta accreta spectrum: A case described using superb microvascular imaging.

We present a case of a 34-year-old pregnant woman with a prior cesarean delivery presenting with placenta previa. Placenta previa accreta was diagnosed from missing decidual flow signals using superb microvascular imaging (SMI). At 31 weeks' gestation, B-mode ultrasonography showed that the placenta was attached to the anterior uterine segment, extending over the internal cervical os. In normally appearing myometrium, SMI demonstrated double layers of flow signals underneath the placental basal plate, corresponding to myometrial and decidual flows. The thin myometrium located on the bladder where sonolucent zones were not visible revealed three different flow patterns in the Doppler signals underneath the basal plate as follows: double layers (both myometrium and decidual tissues present); a single layer (myometrium alone) or no layers (decidual tissues missing). A cesarean hysterectomy was performed at 37 weeks, and histology confirmed the presence of placenta accreta.