New evidence-based diagnostic and management strategies for placenta accreta spectrum disorders

Abstract

The increasing incidence of caesarean delivery (CD) has resulted in an increase in placenta accreta spectrum (PAS), adversely impacting maternal outcomes globally. Currently, more than 90% of women diagnosed with PAS present with a placenta praevia (praevia PAS). Praevia PAS can be reliably diagnosed antenatally with ultrasound, and it is unclear whether magnetic resonance imaging improves diagnosis beyond what can be achieved by skilled ultrasound operators. Therefore, any screening programme for PAS will require improved training in the diagnosis of placental disorders and development of targeted scanning protocols. Management strategies for praevia PAS vary depending on the accuracy of prenatal diagnosis, findings at laparotomy and local surgical expertise. Current epidemiological data for PAS are highly heterogeneous, mainly due to wide variation in the clinical criteria used to diagnose the condition at birth. This significantly impacts research into all aspects of the condition, especially comparison of the efficacy of different management strategies.

Keywords: Caesarean hysterectomy; Increta; Percreta; Placenta accreta; Prenatal diagnosis; Ultrasound imaging.

Fig 1:

Diagram showing an anterior placenta previa on a caesarean scar and the different grades of placenta previa accreta: Creta (PC) where placental (P) villi adhere to the myometrium (M), Increta (PI) where the villi invade the myometrium and Percreta (PP) where the villi invade the entire myometrium and cross the uterine serosa (S). From reference 50.

Fig 2:

Diagram showing an anterior placenta previa accreta combining areas of abnormal adherence and invasion: Creta (PC), Increta (PI) and Percreta (PP). D= Decidua; M= myometrium; S= Serosa. From reference 50.

Fig 3:

Large myometrial dehiscence at 35 weeks (arrow) due to multiple prior CDs creating a “uterine window” where part of the underlying placenta tissue is visible through the serosa mimicking a placenta percreta.