SymptomsPlacentia previa refers to implantation of the placenta
over the cervical os in advance of the fetal presenting part. It
complicates in 200 pregnancies, and accounts for 20% of all cases
of antepartum hemorrhageOther causes of antepartum hemorrhage
include placental abruption (see chapter 47), vasa previa(see
chapter 67), early labor, and genital tract lesions (cervical
polyps or erosions)CAUSESWhen a woman presents with antepartum
hemorrhage, pelvic examination should be avoided until placenta
previa is excluded on ultrasound.Other causes of antepartum
hemorrhage include placental abruption (see chapter 47), vasa
previa(see chapter 67), early labor, and genital tract lesions
(cervical polyps or erosions).
CAUSESMANAGEMENT IN THE SETTING OF PLACENTA PREVIAThe goal of
antepartum management in the setting of placenta previa is to
maximize fetal maturation while minimizing risk to mother and
fetus. Nonreassuring fetal testing (fetal distress) and excessive
maternal hemorrhage are contraindications to expectant management,
and may necessitate immediate cesarean irrespective of gestational
age. Outpatient management may be an option for women with a single
small bleed if they can comply with restrictions on activity and
maintain proximity to a hospital. Placenta previa may resolve with
time, thereby permitting vaginal delivery.
Vaginal delivery is rarely appropriate in the setting of
placenta previa, but may be indicated in the setting of
intrauterine fetal demise, fetal malformation(s) incompatible with
life, advanced labor with engagement of the fetal head and minimal
vaginal bleeding, or an indicated delivery with a previable
fetus
