Summary
Out of a total of 25 551 deliveries, the diagnosis of placenta praevia requiring a caesarean section was made in 124 patients (0.48 per cent). The risk of placenta praevia with an unscarred uterus was 0.42 per cent. The risk increased with the number of previous caesarean sections to 22.2 per cent in patients who had four or more sections.
Patients who had placenta praevia and an unscarred uterus had a 3 per cent risk of having placenta accreta. With previous caesarean section and placenta praevia, the risk increased linearly with the number of previous sections to 50 per cent in patients who had had 4 or more caesarean sections.