上海交通大学医学院：《妇产科学》（双语） 18 Placenta previa

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

F loure 33-2, Normal Figure 33-3, Lo placenta Figure 33-4. Partial Figure 33-5, Complete implantation placenta previa placenta previa

classification

Manifestation Painless hemorrhage 1. The most characteristic symptom 2. Time: late pregnancy(after the 28th week) and delivery 3. Characteristics: sudden, painless and profuse Cause of bleeding Mechanical separation of the placenta from its implantation site, either during the formation of the lower uterine segment, during effacement and dilatation of the cervix in labor. Placentitis. Rupture of the venous in the decidua basalis

Manifestation • Painless hemorrhage 1. The most characteristic symptom 2. Time: late pregnancy (after the 28th week) and delivery 3. Characteristics: sudden, painless and profuse 4. Cause of bleeding Mechanical separation of the placenta from its implantation site, either during the formation of the lower uterine segment, during effacement and dilatation of the cervix in labor. Placentitis. Rupture of the venous in the decidua basalis

Manifestation Anemia or shock repeated bleeding-anemia heavy bleeding→ shock Abnormal fetal position a high presenting part breech presentation(often)

Manifestation • Anemia or shock repeated bleeding→ anemia heavy bleeding→ shock • Abnormal fetal position a high presenting part breech presentation (often)

Diagnosis History 1. Painless hemorrhage 2. At late pregnancy or delivery History of curettage or C

Diagnosis • History 1. Painless hemorrhage 2. At late pregnancy or delivery 3. History of curettage or CS

Diagnosis Signs 1. Abdominal findings 1) Uterus is soft, relaxed and nontender 2) Contraction may be palpated. 3) A high presenting part cant be pressed into the pelvic inlet. Breech presentation 4) Fetal heart tones maybe disappear(shock or abruption)

Diagnosis • Signs 1. Abdominal findings 1) Uterus is soft, relaxed and nontender. 2) Contraction may be palpated. 3) A high presenting part can’t be pressed into the pelvic inlet. Breech presentation 4) Fetal heart tones maybe disappear (shock or abruption)