Placenta praevia without antepartum haemorrhage.

The incidence of placenta praevia praevia in a series in a series of 26,155 patients was 0.9%; in 81 of the 238 patients (34%) there was no antepartum haemorrhage. Placenta praevia was known to be present before delivery in only 12 of the latter group, the condition being diagnosed after vaginal delivery in 17 and at Caesarean section in 52. Approximately 40% of patients with placenta praevia who deliver vaginally have had no antepartum haemorrhage.