Accreta placentation

In the 1930’s the prevalence of placenta accreta spectrum (PAS) disorders was about 1 in 30,000 births but now the rate has increased to 1 in 800-1000 births.

The main risk factor for PAS is previous cesarean section delivery and placenta previa in the current pregnancy.

In the presence of placenta previa the risk of PAS increases from 3% in those without a previous cesarean section to about 10%, 40% and 60% after 1, 2 and 3 previous cesarean sections, respectively.

The main adverse effect of cesarean delivery is failure of adequate healing of the myometrium leaving a gap. The scar tissue is poorly vascularized, less elastic and prone to rupture during labor in subsequent pregnancies and the risk increases with increasing number of cesarean sections.