The tramline sign for abnormally invasive placenta using Crystal Vue with flow.

Objectives To evaluate the diagnostic benefit of using three-dimensional colour imaging with post-processing Crystal Vue Flow (Samsung Medison, Republic of Korea) software to assess 6 cases of suspected abnormally invasive placenta (AIP). Methods Six patients with suspected major placenta previa were evaluated. 83% of the patients had 1 or more previous Caesarean sections. B-mode transabdominal sonography using a WS80A Elite system was performed and colour Doppler was then applied to map the vascularisation of the uterine serosa-bladder interface. 3D colour volumes were obtained from a sagittal section of the uterus bisecting a partially full bladder and processed using Crystal Vue Flow. Results In one case of placenta previa without suspicion of AIP, Crystal Vue Flow revealed a ‘tramline’ like appearance of the intact bladder mucosa and uterine myometrial interface (Fig 1,2). In the other 5 cases there was abnormal vascularity at the uterovesical fold with partial obliteration of the ‘tramlines’ on the rendered volume, suggestive of an AIP (Fig 3,4). The degree of vascular invasion and obliteration of the ‘tramline’ sign appeared strongly indicative of the severity of AIP. The ultrasound appearances were corroborated on MRI and at delivery the diagnosis of AIP was consistent with antenatal sonographic findings. Conclusions Crystal Vue Flow imaging may add valuable information when diagnosing and determining the type of AIP. Greater diagnostic certainty of AIP will allow improved multi-disciplinary input and decision-making regarding timing and place of delivery and will enable improved patient counselling.