PLACENTA PREVIA

Lin Qi De

Definition

Placenta previa: Abnormal

location of the placenta over ,or in

close proximity to the internal os.

Incidence: approximately 1 /250

pregnancy

nulliparas: 1/1000~1/1500

pregnancy

grandmultiparas: 1/20

ClassificationComplete (total) placenta previa: entire cervical os is covered

Partial placenta previa:the margin of the placenta extends across but not all of the internal os.

Marginal:edge of the placenta lies adjacent to the internal os

Low lying placenta:placenta is located near but not directly adjacent to the internal os.

EtiologyMechanism: abnormal vascularization

Predisposing factors:

•Twin pregnancy

•Increasing maternal age

•Increasing parity

•Previous cesarean section

diagnosisPainless vaginal bleed:

first bleeding episode is 29~30 weeks

Ultrasonography:

benefit in localizing the placenta and diagnosis placenta previa

CautionDouble setup vaginal examination

No digital vaginal or rectal examination is preformed in case of placenta previa . Only as a final and definitive event and only under conditions of double set up.

This procedure involves careful evaluation of the cervix in the operation room with full preparations for rapid cesarean section.

ManagementBasic management

•Initial hospitalization with hemodynamic stabilization

•Enforced bed rest

•Restrictions of activity

Expectant management

(allow for further fetal growth and maturation)

•Blood transfusion is given as

necessary

•Amniocentesis for fetal lung maturity

testing

•Cesarean birth if fetus is thought to

be mature

Indication of vaginal delivery

•Delivery can be accomplished with minimal blood loss

•Fetus is dead

•Major fetal malformation

Complication

•Placenta previa accreta

•Postpartum hemopphage

•Increasing maternal mortality and perinatal mortality