A prospective cohort study: can advanced ultrasonography replace magnetic resonance imaging in the diagnosis of placental adhesion disorders?

Objectives: To define and compare the diagnostic accuracy of ultrasonography (USG) and magnetic resonance imaging (MRI) for the placental adhesive disorder (PAD). Methods: A prospective study was conducted between January 2019 and February 2020 in a tertiary referral university hospital. A total of 115 placenta previa cases were included in the study during the third trimester of gestation. USG examination was performed, and the placenta was scanned in a systematic manner using gray-scale ultrasound, color Doppler flow mapping, and 3-D imaging for each participant. Thereafter, all participants underwent an MRI examination. USG and MRI findings were compared with histopathological findings. Results: Loss of the retroplacental sonolucent zone (71% [95% CI 47-88]) and an irregular retroplacental sonolucent zone (71% [95% CI 47-88]) were the most sensitive USG parameters. For MRI, the uterine bulging parameter was the most sensitive (60% [95% CI 36-80]) and specific (91% [95% CI 83-96]) findings, and it had the highest accuracy rate (85% [95% CI 77-91]). Overall, the USG sensitivity, specificity, and accuracy rates were 77% (95% CI 54-92), 87% (95% CI 79-93), and 85% (95% CI 77-91), respectively. The MRI sensitivity, specificity, and accuracy rates for all participants were 81% (95% CI 59-94), 85% (95% CI 76-92), and 84% (95% CI 76-90), respectively. Conclusions: In the diagnosis of PAD, the specificity and accuracy of USG are higher than that of MRI, whereas the sensitivity of MRI is better than that of USG.