Underlying Clinical Features
To improve understanding of the ultrasound signs it is very important to consider the underlying clinical feature that the signs represent. This will help improve interpretation and reduce the false positives e.g. due to confusion between placental lacunae and simple lakes.
Loss of retro-placental clear zone
See Clear Zone page for description and images
Lacunae and feeder vessels
See Placental lacuna page for description and images
See Placental Bulge page for description and images
Both interruption of the bladder wall and bridging vessels arise from the same phenomenon - the matt of tangled blood vessels in the uterine serosa and the uterovesical fold of peritoneum between the anterior uterine wall and posterior bladder. It is important to note this is vascularity in the serosa covering the uterus not in the placenta or residual myometrium.
See here for examples.