1. PLACENTA PREVIA Lin Qi De

2. 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

3. Classification Complete (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.

4. Etiology Mechanism: abnormal vascularization Predisposing factors: Twin pregnancy Increasing maternal age Increasing parity Previous cesarean section

5. diagnosis Painless vaginal bleed: first bleeding episode is 29~30 weeks Ultrasonography: benefit in localizing the placenta and diagnosis placenta previa

6. Caution Double 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.

7. Management Basic management Initial hospitalization with hemodynamic stabilization Enforced bed rest Restrictions of activity

8. 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

9. Indication of vaginal delivery Delivery can be accomplished with minimal blood loss Fetus is dead Major fetal malformation

10. Complication Placenta previa accreta Postpartum hemopphage Increasing maternal mortality and perinatal mortality