ABRUPTIO PLACENTAE
Definitions
Abruptio placenta refers to premature separation of a
normally implanted placenta after twenty weeks of
gestation, but prior to delivery of the infant
The immediate cause of the separation is rupture of
defective maternal vessels in the decidua basalis, where it
interfaces with the placental anchoring villi.
Rarely, the bleeding can originate from the fetal-placental
vessels
The accumulating blood splits the decidua, separating a
thin layer with its placental attachment from the uterus.
The resultant hematoma may be small and self-limited
(partial abruption) or may continue to dissect through the
placental-decidual interface leading to complete or near
complete placental separation (total abruption)
Since the detached portion of the placenta is unable to
exchange gases and nutrients, the fetus can become
compromised if the area of separation is large.
Classification
Two principal forms of premature separation of the
placenta may be recognized depending on whether the
resulting hemorrhage is external or concealed
Concealed form:
(20%), the hemorrhage is confined within the uterine
cavity, detachment of the placenta may be complete, and
the complications are often severe.
Approximately 10% of abruptions are associated with
clinically significant coagulopathies (disseminated
intravascular coagulation [DIC]).
External form:
, (80%), the blood drains through the cervix, placental
detachment is more likely to be incomplete, and the
complications are fewer and less severe.
Hemorrhage from an incompletely detached placenta may
sometimes be concealed by intact membranes, in which
case it is said to be relatively concealed.
Occasionally, the placental detachment involves only the
margin or placental rim.
Here, the most important complication is the possibility of
premature labor.
Etiology
Predisposing factors include
Cigarette smoking: Cigarette smoking increases a
patient's overall risk of placental abruption
Cocaine abuse: The hypertension and increased levels of
catecholamines caused by cocaine abuse are thought to
be responsible for a vasospasm in the uterine blood
vessels that causes placental separation and abruption
Trauma: Abdominal trauma is a major risk factor for
placental abruption.
External or internal version, automobile accident,
abdominal trauma directly transmitted to an anterior
placenta
Thrombophillia: Some literature supports the association
of specific thrombophilias, such as factor V Leiden
mutation, prothrombin gene mutation (A20210 mutation),
hyperhomocysteinemia, activated protein C resistance,
antithrombin III deficiency, and anticardiolipin
immunoglobulin G antibodies, and this risk may be
independent of the presence of preeclampsia.
The presence of a thrombophilia may also influence the
severity of the abruption
Other notable risk factors include the following:
Previous placental abruption
Chorioamnionitis
Definitions
Abruptio placenta refers to premature separation of a
normally implanted placenta after twenty weeks of
gestation, but prior to delivery of the infant
The immediate cause of the separation is rupture of
defective maternal vessels in the decidua basalis, where it
interfaces with the placental anchoring villi.
Rarely, the bleeding can originate from the fetal-placental
vessels
The accumulating blood splits the decidua, separating a
thin layer with its placental attachment from the uterus.
The resultant hematoma may be small and self-limited
(partial abruption) or may continue to dissect through the
placental-decidual interface leading to complete or near
complete placental separation (total abruption)
Since the detached portion of the placenta is unable to
exchange gases and nutrients, the fetus can become
compromised if the area of separation is large.
Classification
Two principal forms of premature separation of the
placenta may be recognized depending on whether the
resulting hemorrhage is external or concealed
Concealed form:
(20%), the hemorrhage is confined within the uterine
cavity, detachment of the placenta may be complete, and
the complications are often severe.
Approximately 10% of abruptions are associated with
clinically significant coagulopathies (disseminated
intravascular coagulation [DIC]).
External form:
, (80%), the blood drains through the cervix, placental
detachment is more likely to be incomplete, and the
complications are fewer and less severe.
Hemorrhage from an incompletely detached placenta may
sometimes be concealed by intact membranes, in which
case it is said to be relatively concealed.
Occasionally, the placental detachment involves only the
margin or placental rim.
Here, the most important complication is the possibility of
premature labor.
Etiology
Predisposing factors include
Cigarette smoking: Cigarette smoking increases a
patient's overall risk of placental abruption
Cocaine abuse: The hypertension and increased levels of
catecholamines caused by cocaine abuse are thought to
be responsible for a vasospasm in the uterine blood
vessels that causes placental separation and abruption
Trauma: Abdominal trauma is a major risk factor for
placental abruption.
External or internal version, automobile accident,
abdominal trauma directly transmitted to an anterior
placenta
Thrombophillia: Some literature supports the association
of specific thrombophilias, such as factor V Leiden
mutation, prothrombin gene mutation (A20210 mutation),
hyperhomocysteinemia, activated protein C resistance,
antithrombin III deficiency, and anticardiolipin
immunoglobulin G antibodies, and this risk may be
independent of the presence of preeclampsia.
The presence of a thrombophilia may also influence the
severity of the abruption
Other notable risk factors include the following:
Previous placental abruption
Chorioamnionitis
