Table 3.
Ultrasound sign definitions for PAS disorders.
| US finding | EW-AIP definition |
|---|---|
| 2D grayscale | |
| Loss of “clear zone” | Loss, or irregularity, of the hypoechoic plane in the myometrium underneath the placental bed (“clear zone”) |
| Abnormal placental lacunae | Presence of numerous lacunae including some that are large and irregular (Finberg grade 3), often containing turbulent flow visible on grayscale imaging |
| Bladder wall interruption | Loss or interruption of the bright bladder wall (hyperechoic band or “line” between the uterine serosa and bladder lumen) |
| Myometrial thinning | Thinning of the myometrium overlying the placenta to <1 mm or undetectable |
| Placental bulge | Deviation of the uterine serosa away from the expected plane, caused by abnormal placental tissue into neighboring organ, typically bladder; uterine serosa appears intact, but outline shape is distorted |
| Focal exophytic mass | Placental tissue seen breaking through the uterine serosa and extending beyond it; most often seen inside the filled urinary bladder |
|
| |
| 2D color Doppler | |
| Uterovesical hypervascularity | Striking amount of color Doppler signal seen between the myometrium and posterior wall of the bladder; this sign probably indicates numerous closely packed tortuous vessels in that region (demonstrating multidirectional flow and aliasing artifact) |
| Subplacental hypervascularity | Striking amount of color Doppler signal seen in the placental bed; this sign probably indicates numerous closely packed tortuous vessels in that region (demonstrating multidirectional flow and aliasing artifact) |
| Bridging vessels | Vessels appearing to extend from the placenta, across the myometrium and beyond the serosa into the bladder or other organs; often running perpendicular to the myometrium |
| Placental lacuna feeder vessels | Vessels with high-velocity blood flow leading from the myometrium into placental lacunae, causing turbulence upon entry |
|
| |
| 3D ultrasound+power Doppler | |
| Intraplacental hypervascularity | Complex, irregular arrangement of numerous placental vessels, exhibiting tortuous courses and varying calibers |
| Placental bulge | Same as in 2D |
| Focal exophytic mass | Same as in 2D |
| Bridging vessels | Same as in 2D |
From Collins et al. [64] with permission.