Diagnostic Performance of Ultrasound and MRI in Placenta Accreta Spectrum

Abstract Placenta accreta spectrum (PAS) disorders cause significant maternal morbidity due to abnormal placental adherence and invasion. Accurate prenatal diagnosis is essential for appropriate obstetric planning. Ultrasonography (USG) is the first-line imaging modality, with magnetic resonance imaging (MRI) used as a complementary tool. The aim of the study is to compare the diagnostic performance of USG and MRI in the prenatal diagnosis of PAS. This prospective observational study included 50 pregnant women beyond 20 weeks of gestation with suspected placental abnormality. All patients underwent grayscale and color Doppler USG followed by non-contrast MRI. Sonographic markers included placental lacunae, loss of retroplacental clear space, increased vascularity, myometrial thinning, and disruption of the bladder–uterine interface. MRI features assessed were dark intraplacental T2-hypointense bands, abnormal placental contour, uterine bulging, myometrial thinning, loss of uterine serosal interface, and bladder tenting. Imaging findings were correlated with intraoperative and histopathological outcomes. PAS was confirmed in 23 cases (46%). USG showed a sensitivity of 86.96% and specificity of 81.48%, while MRI demonstrated higher sensitivity (91.3%) and specificity (88.9%). Placental lacunae and increased vascularity were the most sensitive USG markers, whereas abnormal placental contour and myometrial thinning were sensitive MRI findings. USG is an effective screening tool for PAS, while MRI improves specificity and assessment of invasion depth, aiding surgical planning.