Performance of antenatal imaging to predict placenta accreta spectrum degree of severity

In cases of placenta accreta spectrum, a precise antenatal diagnosis of the suspected degree of invasion is essential for the planning of individual management strategies at delivery. The aim of this work was to evaluate the respective performances of ultrasonography and magnetic resonance imaging for the antenatal assessment of the severity of placenta accreta spectrum disorders included in the database. The secondary objective was to identify descriptors related to the severity of placenta accreta spectrum disorders.

All the cases included in the database for which antenatal imaging data were available were analyzed. The rates of occurrence of each ultrasound and magnetic resonance imaging descriptor were reported and compared between the Group "Accreta-Increta" (FIGO grades 1 & 2) and the Group "Percreta" (FIGO grade 3).

Antenatal imaging data were available for 347 women (347/442, 78.5%), of which 105 were included in the Group "Accreta - Increta" (105/347, 30.2%) and 213 (213/347, 61.4%) in the Group "Percreta". Magnetic resonance imaging was performed in addition to ultrasound in 135 women (135/347, 38.9%). After adjustment for all ultrasound descriptors in multivariate analysis, only the presence of a bladder wall interruption was associated with a significant higher risk of percreta (Odds ratio 3.23, Confidence interval 1.33-7.79). No magnetic resonance imaging sign was significantly correlated with the degree of severity.

The performance of ultrasound and magnetic resonance imaging to discriminate mild from severe placenta accreta spectrum disorders is very poor. To date, the benefit of additional magnetic resonance imaging has not been demonstrated.