Placenta praevia percreta, with bladder invasion, was diagnosed at 29 weeks of amenorrhoea with colour Doppler which visualized vascular bundles leaving the placenta and reaching the lower part of the bladder. These bundles were identified as including arterial elements with pulsed Doppler. The criteria for the diagnosis of placenta accreta with ultrasonography and colour Doppler have been presented in the literature. This prenatal diagnosis allowed adapted preoperative management and intensive care, however air embolism could not be avoided and the patient died at the end of the operation.