Placenta praevia

Placenta praevia (placenta previa AE) is an obstetric complication in which the placenta is attached to the uterine wall close to or covering the cervix . It can sometimes occur in the later part of the first trimester, but usually during the second or third. It is a leading cause of antepartum haemorrhage (vaginal bleeding). It affects approximately 0.5% of all labours. No specific cause of placenta previa has yet been found but it is hypothesiz... more

Placenta praevia (placenta previa AE) is an obstetric complication in which the placenta is attached to the uterine wall close to or covering the cervix . It can sometimes occur in the later part of the first trimester, but usually during the second or third. It is a leading cause of antepartum haemorrhage (vaginal bleeding). It affects approximately 0.5% of all labours. No specific cause of placenta previa has yet been found but it is hypothesized to be related to abnormal vascularisation of the endometrium caused by scarring or atrophy from previous trauma, surgery, or infection. In the last trimester of pregnancy the isthmus of the uterus unfolds and forms the lower segment. In a normal pregnancy the placenta does not overlie it, so there is no bleeding. If the placenta does overlie the lower segment, it may shear off and a small section may bleed. Women with placenta previa often present with painless, bright red vaginal bleeding. This bleeding often starts mildly and may increase... less