Placenta accreta may be suspected prior to surgery, but the actual diagnosis is only confirmed at surgery. This prospective and observational study was performed to assess whether preparations should be made for potential massive blood loss prior to Caesarean surgery in all patients with suspected placenta accreta. Patients were classified as high or low suspicion for placenta accreta based on ultrasonography and clinical factors. Among 28 suspected cases of placenta accreta, diagnosis was confirmed at surgery in 50% (12/17 high and 2/11 low suspicion) cases. Hysterectomy was only performed in the 12 high suspicion patients with placenta accreta (p < 0.001). High suspicion patients required more blood transfusions: mean(SD) 6.5 (7.0) units vs 1.09 (1.1) units, p = 0.017. Anaesthetists should be prepared for major haemorrhage in all cases of suspected placenta accreta, although use of a system to grade level of suspicion may identify those at greater risk.