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),
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
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
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,
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
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)
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 can’t be pressed into
the pelvic inlet,Breech presentation
4) Fetal heart tones maybe disappear (shock or
abruption)
Diagnosis
? Speculum examination (窥阴检查 )
Rule out local causes of bleeding,such as
cervical erosion or polyp or cancer,
? Limited vaginal examination (seldom used)
Palpation of the vaginal fornices to learn if
there is an intervening bogginess between the
fornix and presenting part,
? Rectal examination is useless and dangerous
Diagnosis
? Ultrasonography
1,The most useful diagnostic method,95%
2,Not make the diagnosis at the mid pregnancy,
(≥ 34 weeks)
? MRI
? Check the placenta and membrane after
delivery
Differential Diagnosis
? Placental abruption
vagina bleeding with pain,tenderness of uterus,
? Vascular previa
? Abnormality of cervix
cervical erosion or polyp or cancer
Effects
? obstetrical hemorrhage
? Placenta accreta
? Anemia and infection
? Premature labor or fetal death or fetal
distress
Treatments
? Expectant therapy
1,Rest,keep the bed
2,Controlling the contraction,MgSO4
3,Treatment of anemia
4,Preventing infection
Treatments
? Termination of pregnancy
1,CS
1) total placenta previa (36th week),Partial
placenta previa (37th week) and heavy
bleeding with shock
2) Preventing postpartum hemorrhage,pitocin
and PG
3) Hysterectomy,Placenta accreta or
uncontroled bleeding
Treatments
2,Vaginal delivery
Marginal placenta previa
Vaginal bleeding is limited
END
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),
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
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
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,
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
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)
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 can’t be pressed into
the pelvic inlet,Breech presentation
4) Fetal heart tones maybe disappear (shock or
abruption)
Diagnosis
? Speculum examination (窥阴检查 )
Rule out local causes of bleeding,such as
cervical erosion or polyp or cancer,
? Limited vaginal examination (seldom used)
Palpation of the vaginal fornices to learn if
there is an intervening bogginess between the
fornix and presenting part,
? Rectal examination is useless and dangerous
Diagnosis
? Ultrasonography
1,The most useful diagnostic method,95%
2,Not make the diagnosis at the mid pregnancy,
(≥ 34 weeks)
? MRI
? Check the placenta and membrane after
delivery
Differential Diagnosis
? Placental abruption
vagina bleeding with pain,tenderness of uterus,
? Vascular previa
? Abnormality of cervix
cervical erosion or polyp or cancer
Effects
? obstetrical hemorrhage
? Placenta accreta
? Anemia and infection
? Premature labor or fetal death or fetal
distress
Treatments
? Expectant therapy
1,Rest,keep the bed
2,Controlling the contraction,MgSO4
3,Treatment of anemia
4,Preventing infection
Treatments
? Termination of pregnancy
1,CS
1) total placenta previa (36th week),Partial
placenta previa (37th week) and heavy
bleeding with shock
2) Preventing postpartum hemorrhage,pitocin
and PG
3) Hysterectomy,Placenta accreta or
uncontroled bleeding
Treatments
2,Vaginal delivery
Marginal placenta previa
Vaginal bleeding is limited
END
