Table 1. Diagnostic methods and its findings of placenta accreta spectrum.

• Ultrasonography

○ The presence of many low-intensity areas (placental lacunae) in the placenta; a Swiss cheese-like appearance.

○ Loss of the low-intensity area (sonolucent zone, retroplacental clear space) between the placenta and myometrium.

○ Irregularity and interruption of the bladder border.

○ Thinning (≤1 mm) of the myometrium, protrusion of the placenta toward the bladder.

• Color-Doppler and pulse-Doppler ultrasonography

○ There are diffuse blood vessels (lacunar flow) in the placenta with pulsating rapid venous flow.

○ There are myometrial or subplacental blood vessels with pulsating turbulent venous flow.

○ There are dilated blood vessels in the bladder and myometrium with arterial flow showing a low resistance index.

○ Markedly dilated subplacental blood vessels with pulsating venous flow.

• Biomarker testing

○ Elevated α-fetoprotein levels.

○ Cell-free fetal DNA, placental mRNA, DNA microarray assay.

Source: Reproduced with permission of Takeda S. Cesarean section for placenta previa and placenta previa accrete spectrum. In: Takeda S, Hiramatsu Y, Konishi I, Sakuragi N, eds. OGS NOW, No.3. Cesarean Section. Mastering the Essential and Practical Surgical Procedures. Tokyo: Medical View; 2010:102–115. Copyright © Medical View.