Introduction:
Placenta accreta spectrum (PAS) is a term that comprise abnormal placental invasion disorders of the uterine wall. According to the depth of invasion, it ranges from placental invasion in contact with myometrium (placenta accreta), into myometrium (placenta increta), or beyond myometrium (placenta percreta) (1, 2). PAS is an obstetric emergency that may be complicated by emergency hysterectomy, intraoperative surgical complications, massive transfusion, hemorrhagic shock, and even maternal death if not managed efficiently (3). Previous cesarean deliveries, placenta previa and advanced maternal age are recognized strong risk factors of PAS, all of which, have become more prevalent among contemporary population (4, 5). Therefore, PAS is no longer a rare disorder in modern practice; the incidence of PAS has increased from approximately 1 in 30,000 deliveries before 1950 to 3 in 1000 deliveries in the current decade (6).
Currently, cesarean hysterectomy is the standard management of PAS. Despite surgical risks, loss of uterine function, and psychological sequences, cesarean hysterectomy permits elective intervention under controlled settings to minimize blood loss (7). Several uterus-preserving procedures have been evaluated including preoperative uterine artery embolization via catherization (2), open surgical devascularization of uterus (8), hysteroscopy resection of residual placenta with or without methotrexate administration (9) and leaving the placenta in situ (10). However, in most instances, data is derived from case series and small studies, and these procedures may be associated with significant blood loss, infection, bleeding, and secondary hysterectomy (11).
High intensity focused ultrasound (HIFU) is a non-invasive treatment that utilizes ultrasound waves to cause thermal damage of a targeted lesion without affecting adjacent tissue (12). Since 1950s, HIFU has been investigated in management of various benign and malignant solid tumors (13). Uses has extended to uterine fibroids, cesarean scar pregnancy and adenomyosis (14-16). Recently, HIFU has been proposed as a non-invasive treatment that could preserve the uterus in women with PAS without increasing surgical morbidity and risk of significant blood loss. In this systematic review, we aim at assessing clinical outcomes of HIFU and comparing safety and efficacy of this modality to other uterus-preserving procedures in women with PAS. In addition, we aim at investigating inherited restrictions of these studies and future directives that may improve practice of conservative management of PAS.