Placenta previa Liu wei Department of ob gy Ren ji hospital
Placenta Previa Liu Wei Department of Ob & Gy Ren Ji hospital
General considerations Definition In placenta previa, the placenta is implanted in the lower uterine segment and located over the internal os. It constitutes an obstruction of descent of the presenting part. Main cause of obstetrical hemorrhage Incidence 0.24%-1.57%(our country)
General considerations • Definition In placenta previa, the placenta is implanted in the lower uterine segment and located over the internal os. It constitutes an obstruction of descent of the presenting part. • Main cause of obstetrical hemorrhage • Incidence 0.24%-1.57% (our country)
Etiology Uncertain High risk factors 1. maternal age: >35 years 2. multiparity: 85%-90% prior cesarean delivery: 5 times smoking
Etiology • Uncertain • High risk factors 1. maternal age: >35 years 2. multiparity: 85% - 90% 3. prior cesarean delivery: 5 times 4. smoking
Etiology Causes 1. Endometrial abnormality Scared or poorly vascularized endometrium in the corpus 2) Curettage, Delivery, cs and infection of endometrium Placental a normality Large placenta(multiple pregnancy), succenturiate lobe(副胎盘) 3. Delayed development of trophoblast
Etiology • Causes 1. Endometrial abnormality 1) Scared or poorly vascularized endometrium in the corpus. 2) Curettage, Delivery, CS and infection of endometrium 2. Placental abnormality Large placenta (multiple pregnancy), succenturiate lobe (副胎盘) 3. Delayed development of trophoblast
Classification Total placenta previa The internal cervical os is covered completely by pl Macenta Partial placenta previa The internal os is partially covered by placenta Marginal placenta previa The edge of the placenta is at the margin of the intenal os
Classification • Total placenta previa The internal cervical os is covered completely by placenta • Partial placenta previa The internal os is partially covered by placenta • Marginal placenta previa The edge of the placenta is at the margin of the intenal os