Real increasing incidence of hysterectomy for placenta accreta following previous caesarean section

Placenta accreta, morbid adherence to the uterus to the myometrium, is commonest in association with placenta previa in women previously delivered by caesarean section (CS). It has become proportionally a greater cause of major maternal morbidity and mortality as the frequency of other serious obstetric complications has declined. The aim of this study was to examine the incidence of placenta accreta in the context of a rising caesarean delivery rate.

Retrospective review of the incidence of placenta accreta in parous women during the 36 years 1975-2010. Cases were identified from hospital records and then correlated with pathological reports. The incidence of placenta accreta was analysed in the context of women previously delivered by CS.

During the 36-year period in our unit, 157,162 multiparous women delivered, of whom 15,151 (9.6%) had a previous CS scar. The institutional incidence of CS rose from 4.1% in 1975 to 20.7% in 2010. Twenty-five parous women, all with a previous CS, had placenta accreta requiring hysterectomy. The overall incidence of placenta accreta was 1.65 per 1000 parous women with a previous CS, but was low (1.06/1000) until 2002. From 2003 to 2010 the incidence rose to 2.37/1000 previous CS deliveries (OR 2.2; 95% CI 1.05-5.1).

The frequency of placenta accreta correlated steadily with the CS rate until 2000. Since then, the incidence has nearly doubled in women with previous CS scars, suggesting an additional causative influence on risk.