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.