Placenta Previa refers to a
situation where the placenta, which should normally grow in the upper part of
the uterus, grows in the lowest part instead, thus covering (either partially
of totally) the cervical opening. It is indicated by bright red vaginal bleeding
in the second to third trimester of pregnancy. The bleeding is usually
painless. In pregnancy, a woman can lose up to 40% of the blood volume without
any signs of shock; this may explain why the patient has normal vital signs
even with blood loss.