Ultrasound, MRI may help in diagnosis of placenta accreta spectrum disorder: Study

On ultrasound and MRI alike, the placental bulge sign represents deeper venous invasion in PAS--the focal area of myometrial-placental bulging beyond the normal uterine contour. Dighe and colleagues' retrospective study included 62 pregnant women (mean age, 33.2 years) with clinically suspected PAS who underwent both ultrasound and MRI. Blinded to final diagnoses, two maternal-fetal medicine specialists for ultrasound and three abdominal radiologists for MRI independently reviewed images for their respective modality. Using intraoperative and pathologic findings, alongside the International Federation of Gynaecology and Obstetrics classification, patients were separated into those with and without severe PAS.

"In diagnosing severe PAS," Dighe et al. noted, "placental bulge sign achieved on ultrasound an accuracy of 85.5%, the sensitivity of 91.7%, and specificity of 76.9%, and on MRI an accuracy of 90.3%, sensitivity of 94.4%, and specificity of 84.6%." Ultimately, the placental bulge was an independent predictor of severe PAS on ultrasound (odds ratio=8.94) and MRI (odds ratio=45.67).

"Placental bulge sign on either prenatal ultrasound or MRI may help diagnose severe PAS warranting hysterectomy rather than conservative management," the authors of this AJR article concluded.