Histological Assessment of the Placenta Accreta Spectrum Diagnosed with a 33-MHz Linear Probe during Cesarean Section

As placenta accreta spectrum (PAS) pathologies affect only the extremely thin tissues between the placenta and the uterine myometrium, superficial endometrial damage such as that caused by placenta creta and increta can be diagnosed only through histopathology. We performed direct uterine ultrasound of PAS using an ultrahigh frequency (33 MHz; i33LX9 Aplio i800) linear transducer. Here, we describe two cases with ultrasound images of placentas with PAS and a case without PAS to compare histological findings. In cases of PAS at the previous Cesarean scar, ultrasonography clearly revealed a thin uterine myometrium with some island-shaped sites where placental tissue was focally anchored to the uterine myometrium near the scar. Speckle blood flow pattern was absent at these sites during scanning with B-mode, but was detectable elsewhere. Histopathology samples from the same site revealed that villous tissue was directly attached to the uterine myometrium with a large area of infarction. In another case of diffuse PAS, speckle blood flow pattern was generally absent, and histopathology revealed deep fibrinoid deposits. We believe that histological evaluation following ultrasound use will improve the accuracy of ultrasound diagnosis and perinatal management of PAS in clinical practice.