Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Gynecology and Obstetrics

Objectives: Standardized ultrasound imaging protocols have been developed for the prenatal diagnosis of placenta accreta spectrum disorders (PAS). The aim of this study was to prospectively investigate a cohort of patients at high-risk of PAS using ultrasound signs for the diagnosis of posterior and lateral accreta placentation and evaluate their effectiveness by comparing them with guided microscopic examination. Methods: A cohort of 90 consecutive patients diagnosed as PAS by prenatal ultrasound examination, who were candidates for either cesarean hysterectomy or conservative management, were investigated prospectively using the standardized description of ultrasound signs of PAS proposed by the European Working Group on abnormally invasive placenta (EW-AIP), used -when relevant-to detect posterior and lateral PAS. In all cases, the ultrasound diagnosis of posterior or lateral adhesion/invasion was compared to results of histopathological examination. Guided histologic sampling was used to target abnormally adherent/invasive areas Results: All patients had a history of 1 or more prior cesarean deliveries (CDs) and presented with a low-lying/placenta previa. The overall performance of ultrasound in the antenatal detection of lateral accreta placentation in our cohort was as follows: sensitivity, 73.58 (95% CI, 59.67 to 84.74) %; specificity, 97.30 (95% CI, 85.84 to 99.93) %; positive likelihood ratio (LR+), 27.23 (95% CI, 3.91 to 189.47); negative likelihood ratio (LR{u2013}), 0.27 (95% CI, 0.17 to 0.43) and diagnostic accuracy, 83.33% (74.00 to 90.36%)

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