The Common Vein Copyright 2010
Definition
Placenta previa is a disorder of placental bleeding during pregnancy.
The cause is implantation of the placenta near or overlying the cervical os.
The result is bleeding in late pregnancy.
The structural change is characterized by placental implantation near the cervical os. As the placenta grows, part of the placenta may grow over the cervical os.
The functional changes are characterized by small disruptions in the attachment of the placenta to the endometrium causing placental bleeding through the cervical os.
Women most often present clinically with painless bleeding late in pregnancy. The amount of bleeding varies from small losses to severe hemorrhage.
Diagnosis is made with ultrasound imaging. Treatment depends on the amount of bleeding.
Small amounts of bleeding may be managed expectantly with steroids to promote fetal lung maturity and bed rest. Large bleeds are treated with immediate cesarean delivery.