Accuracy of Three /Four-dimensional Ultrasound in Diagnosing Placenta Accreta Spectrum: A Prospective Study

The placenta accreta spectrum (PAS) which includes accreta, increta, and percreta represents a significant obstetric challenge. PAS complicates as many as 1 per 500 pregnancies and this risk is increased with prior cesarean deliveries. Antenatal diagnosis of PAS allows for multidisciplinary planning and delivery before the onset of labor and/or vaginal bleeding. This approach has reduced maternal morbidity rates, including less blood loss, fewer transfusion requirements and, intraoperative urologic injuries as well as improve fetal outcome.

Ultrasound evaluation, with grayscale and color Doppler imaging, is the recommended first-line modality for diagnosing PAS. Grayscale ultrasound features suggestive of placenta accreta include an inability to visualize the normal retroplacental clear zone, irregularity and attenuation of the uterine-bladder interface, retroplacental myometrial thickness, presence of intraplacental lacunar spaces, and bridging vessels between the placenta and bladder wall when using color Doppler. Magnetic resonance imaging (MRI) has been used to predict the depth of placental invasion, but it is expensive and often not immediately available.

Recently, a new imaging technique utilizing three-dimensional (3D)/four-dimensional (4D) volume rendering ultrasound (VRU) was proposed as a promising tool for the preoperative diagnosis of placenta previa accerta spectrum. By using "crystal vue" and "realistic vue" volume rendering mode, it could detect 11 out of 12 cases (91.6%) of PAS which was subsequently confirmed during surgery. Accordingly, The aim of this study is to examine the diagnostic performance of 3D/four-dimensional (4D) volume rendering ultrasound (VRU) for placenta previa accerta spectrum in correlation with the clinical (operative) and pathological findings.