Posterior placenta accreta spectrum: unraveling distinctive clinical features and diagnostic challenges

Background: Posterior placenta accreta spectrum (PAS) represents a diagnostically challenging subtype of PAS, which has long been overlooked in existing literature due to its relatively low incidence and nonspecific clinical manifestations. Methods: A comprehensive literature search was conducted in PubMed, Web of Science, and other databases, focusing on studies related to the diagnosis and management of posterior PAS. This review systematically analyzes the risk factors, prenatal diagnostic characteristics, and pregnancy outcomes of posterior PAS, with a focus on clarifying the characteristic differences between posterior PAS and PAS involving other uterine locations. Results: Both ultrasound (US) and magnetic resonance imaging (MRI) have limited diagnostic sensitivity for posterior placenta accreta spectrum (PAS): the sensitivity of US ranges from 56.4% to 62%, while the application rate of MRI signs for posterior PAS is 73.5%, and both of which are 20-30% lower than those for anterior PAS. Irregular retroplacental clear zone on US and cervical varices on MRI are prominent diagnostic indicators for the condition. Notably, compared with anterior PAS, posterior PAS is characterized by shallower myometrial invasion and a more favorable prognosis. Conclusions: Posterior PAS has unique diagnostic and clinical features that distinguish it from anterior PAS. Enhanced recognition of its imaging characteristics and targeted management strategies are crucial to improve maternal outcomes. This review fills the literature gap by systematically summarizing the latest evidence on posterior PAS, providing a reference for clinical practice and future research.