VP46.04: The value of sonographic (US) and magnetic resonance imaging in the management of placenta accreta spectrum disorders

To determine the value of US and magnetic resonance imaging (MRI) in the management of placenta accreta spectrum (PAS). A retrospective cohort study was conducted on 77 cases at risk for PAS disorders managed at our institution from January 2013 and July 2019. Imaging modality was determined on a case-by-case basis. US was interpreted by maternal-fetal medicine specialists; MRI, by radiologists with expertise in diagnosis of PAS with knowledge of the US interpretation and clinical risk factors for PAS. Optimal management of cases included elective Caesarean delivery without disrupting the placenta; hysterectomy by gynecologic oncologists if indicated; and embolisation of the uterine arteries arteries in selected cases. The area under the receiver-operator curves was used to compare different diagnostic approaches. No single approach was significantly superior over the other. A history of uterine surgery and placenta previa in the index pregnancy had a predictive value comparable to imaging. MRI as an adjunct to US improved the sensitivity, but not the specificity, of US alone. In 31 cases where MRI was performed as an adjunct, the severity of PAS was up-or downgraded in 17 (55%) of the cases, which, in turn affected the management in 13 (42%). Of the 13 cases, 10 (77%) received optimal management as a result. Patients with a history of uterine surgery and placenta previa in the index pregnancy are at a high risk for PAS and should be managed accordingly regardless of the imaging results. MRI as an adjunct to US may improve the assessment of disease severity in selected cases and thus the management. VP46.04: Table 1. Sensitivity, specificity, positive and negative predictive value of ultrasound alone, US + MRI and clinical history Sensitivity % (n/N) Specificity % (n/N) US = ultrasound; MRI = magnetic resonance imaging; PPV = positive predictive value; NPV = negative predictive value