Placenta previa
The placenta provides the fetus with oxygen and nutrients and takes away
waste such as carbon dioxide via the umbilical cord,
Definition Placenta previa is a
condition that may occur during
pregnancy when the placenta implants
in the lower part of the uterus and
obstructs the cervical opening to the
vagina (birth canal),
Chinese definition
IncidenceThe incidence of placenta previa is
approximately 1 out of 200 births,
increases with each pregnancy,and it
is estimated that the incidence in
women who have had 6 or more
previous deliveries may be as high as 1
in 20 births,
doubled in multiple pregnancy (such as
twins and triplets),
Causes
Endometrium factors:
a scarred endometrium (lining of the uterus)
Curretage for several times
an abnormal uterus
Placental factors
Large
abnormal formation of the placenta,
Development retardation of fertilized egg
Risk factors include multiparity
(previous deliveries),multiple
pregnancy,previous myomectomy
(removal of uterine fibroids through an
incision in the uterus),and a previous
C-section (if the scar is low and close to
the vaginal cervix region),
classification
Complete placenta previa
Partial placenta previa
Marginal placenta previa
Clinical findings
Symptoms
Spotting during the first and second trimesters
Sudden,painless,and profuse vaginal bleeding in
pregnancy during the third trimester (usually after
28 weeks)
Uterine cramping may occur with onset of
bleeding
Bleeding may not occur until after labor starts in
some cases
Signs
The uterus is usually soft and relaxed.
The infant position is oblique ( // ) or
transverse ( == ) in about 15% of cases.
Fetal distress is not usually present unless
vaginal blood loss has been heavy enough
to induce maternal shock,placenta
abruptio,or a cord accident occurs,
No digital examination!
Accessory examinations
Ultrasonography:
Accuracy 95%
34th week
Postpartum examination of placenta
and membrane
7cm
Diagnosis
Differential diagnosis
Complications
Maternal complications
major hemorrhage,shock,and death,
Implanted placenta
Anemia and infection
Fetal complications
Prematurity (infant is less than 36 weeks gestation)
is responsible for about 60% of infant deaths
secondary to placenta previa,
Fetal blood loss or hemorrhage may occur
because of the placenta tearing away from the
uterine wall during labor,It may also occur with
entry into the uterus during a C-section delivery,
Treatment
The course of treatment depends on
the amount of abnormal uterine
bleeding,whether the fetus is
developed enough to survive outside
the uterus,the amount of placenta over
the cervix,the position of the fetus,the
parity (number of previous births) for
the mother,and the presence or
absence of labor,
Early in pregnancy,transfusions may be
given to replace maternal blood loss,
Medications may be given to prevent
premature labor,prolonging pregnancy
to at least 36 weeks,Beyond 36 weeks,
the benefits of additional infant
maturity have to be weighed against
the potential for major hemorrhage,
Cesarean section is the method for
delivery,It has proven to be the most
important factor in reducing maternal
and infant death rates,？
Expectations (prognosis)
The maternal prognosis (probable
outcome) is excellent when managed
appropriately,This is done by
hospitalizing those at risk who are
exhibiting signs and symptoms,and by
performing C-section delivery.
The placenta provides the fetus with oxygen and nutrients and takes away
waste such as carbon dioxide via the umbilical cord,
Definition Placenta previa is a
condition that may occur during
pregnancy when the placenta implants
in the lower part of the uterus and
obstructs the cervical opening to the
vagina (birth canal),
Chinese definition
IncidenceThe incidence of placenta previa is
approximately 1 out of 200 births,
increases with each pregnancy,and it
is estimated that the incidence in
women who have had 6 or more
previous deliveries may be as high as 1
in 20 births,
doubled in multiple pregnancy (such as
twins and triplets),
Causes
Endometrium factors:
a scarred endometrium (lining of the uterus)
Curretage for several times
an abnormal uterus
Placental factors
Large
abnormal formation of the placenta,
Development retardation of fertilized egg
Risk factors include multiparity
(previous deliveries),multiple
pregnancy,previous myomectomy
(removal of uterine fibroids through an
incision in the uterus),and a previous
C-section (if the scar is low and close to
the vaginal cervix region),
classification
Complete placenta previa
Partial placenta previa
Marginal placenta previa
Clinical findings
Symptoms
Spotting during the first and second trimesters
Sudden,painless,and profuse vaginal bleeding in
pregnancy during the third trimester (usually after
28 weeks)
Uterine cramping may occur with onset of
bleeding
Bleeding may not occur until after labor starts in
some cases
Signs
The uterus is usually soft and relaxed.
The infant position is oblique ( // ) or
transverse ( == ) in about 15% of cases.
Fetal distress is not usually present unless
vaginal blood loss has been heavy enough
to induce maternal shock,placenta
abruptio,or a cord accident occurs,
No digital examination!
Accessory examinations
Ultrasonography:
Accuracy 95%
34th week
Postpartum examination of placenta
and membrane
7cm
Diagnosis
Differential diagnosis
Complications
Maternal complications
major hemorrhage,shock,and death,
Implanted placenta
Anemia and infection
Fetal complications
Prematurity (infant is less than 36 weeks gestation)
is responsible for about 60% of infant deaths
secondary to placenta previa,
Fetal blood loss or hemorrhage may occur
because of the placenta tearing away from the
uterine wall during labor,It may also occur with
entry into the uterus during a C-section delivery,
Treatment
The course of treatment depends on
the amount of abnormal uterine
bleeding,whether the fetus is
developed enough to survive outside
the uterus,the amount of placenta over
the cervix,the position of the fetus,the
parity (number of previous births) for
the mother,and the presence or
absence of labor,
Early in pregnancy,transfusions may be
given to replace maternal blood loss,
Medications may be given to prevent
premature labor,prolonging pregnancy
to at least 36 weeks,Beyond 36 weeks,
the benefits of additional infant
maturity have to be weighed against
the potential for major hemorrhage,
Cesarean section is the method for
delivery,It has proven to be the most
important factor in reducing maternal
and infant death rates,？
Expectations (prognosis)
The maternal prognosis (probable
outcome) is excellent when managed
appropriately,This is done by
hospitalizing those at risk who are
exhibiting signs and symptoms,and by
performing C-section delivery.
