OC09.02

Objectives: Abnormally invasive placenta (AIP) has become a worldwide concern. We wished to determine whether ultrasound descriptors also played a role in the prediction of prognosis for AIP. Methods: We carried a retrospective review for those cases of placenta previa totalis with the suspicion of AIP during the period between Feb 2002 and Feb 2018. Exclusion criteria were failure to complete follow-up and the operation was taken before the third trimester. In those enrolled cases, a targeted scanning was directed towards the colour flow signals between the placenta and bladder mucosa. In addition to those ultrasound descriptors described by Ad-hoc International AIP and EW-AIP expert groups, we disclosed the novel ′rail sign′ by colour Doppler ultrasound. The positive ′rail sign′ was defined as two parallel flow signals appearing in the subplacental and bladder mucosa regions with interconnected bridging vessels perpendicular to them. Results: Totally 133 consecutive cases of AIP were enrolled during Caesarean section in the third trimester. Among them, 72 patients were positive for rail sign. Those patients with positive rail sign were prone to have a severe extent of AIP (eg. placenta increta or percreta) (n< 0.001). The most significant difference is patients with positive rail sign had a higher chance of hysterectomy and blood transfusion (n<0.001). In addition, patients with positive rail sign also had a higher likelihood of bladder invasion and ICU admission (n<0.05). The blood loss for patients with positive rail sign is significant higher than rail sign (-) patients (n<0.001). The mean gestational week of delivery for patients with positive rail sign was also earlier than those patients without rail sign. Conclusions: Rail sign identified by colour Doppler ultrasound may distinguish advanced AIP from mild AIP and predicts higher morbidity. Ultrasound descriptors do matter not only for diagnosis, but also for outcome prediction and probably surgical planning.