Placenta Previa

Placenta previa occurs when the placenta has implanted with extension approaching or directly over the internal cervical os. Most cases of placenta previa are actually minor, identified by routine prenatal uterine ultrasounds and do not require any intervention. However, symptomatic cases will often present to the emergency setting with painless vaginal bleeding during the third trimester of pregnancy. When placenta previa is considered, it is one of notable times when the emergency physician should avoid routine digital evaluations of the cervical os to avoid inciting more bleeding. Volumes of bleeding can be significant enough to cause hemorrhagic shock. If the amount of bleeding is small, bed rest and conservative management may be recommended in coordination with an obstetric specialist. However, depending on the amount of bleeding, urgent or emergent cesarean section may be indicated to optimize outcomes for both the mother and fetus. Previa can be confirmed by ultrasound.