816: Prediction of Morbidly adherent placenta using ultrasonographic Placenta Accreta Index (PAI)

Abstract

The current study aims to evaluate the accuracy of an ultrasonographic placenta accreta index (PAI) for diagnosing morbidly adherent placenta (MAP). This study was a prospective cohort study included pregnant women referred to our ultrasound unit in a tertiary university hospital from March 2016 to February 2018 because of suspected MAP on a previous ultrasound examination All women were assessed using the PAI score based on the following: number and size of placental lacunae; presence of bridging vessels; the sagittal smallest myometrial thickness, the uterine-bladder interface thickness and the placental location. Additionally, the number of previous Cesarean deliveries was determined. All ultrasonographic evaluations were performed by an expert level II sonographer. The presence of MAP was determined by the surgeon at delivery and clinical data were recorded at time of delivery. Pathological diagnoses of placental invasion were available only in patients that underwent hysterectomy. In total, 137 pregnant women were included in the study, of whom 33 (24.1%) were diagnosed with MAP. The mean PAI score in women with focal accreta was significantly higher than the PAI score of placenta previa non-accreta (6.50±1.81 vs. 3.63±1.98, p<0.001). Similarly, the mean PAI score in women with total accrete was significantly higher than non-accreta (8.71±0.28 vs. 3.63±1.98, p<0.001). Receiver–operating characteristics (ROC) curve for prediction of MAP using PAI score yielded an area under the ROC curve of 0.911. The best cut-off point was 5.25 with 86% sensitivity and 88% specificity. All sonographic criteria of the PAI were significantly associated with MAP (p<0.0001). ROC curves for prediction of MAP using the number of placental lacunae and smallest myometrial thickness yielded an area under the ROC curve of 0.856 and 0.783 respectively. PAI is highly predictive of morbidly adherent placenta in patients at risk. This allows an adequate pre-operative planning and accurate timing of delivery in such cases