eMedicine Specialties > Obstetrics and Gynecology > Obstetrical Complications

Abruptio Placentae

Author: Shad H Deering, MD, Clinical Assistant Professor, Department of Obstetrics and Gynecology, University of Washington; Medical Director, Andersen Simulation Center, Madigan Army Medical Center
Contributor Information and Disclosures

Updated: Dec 22, 2008

Introduction

Background

Abruptio placentae is defined as the premature separation of the placenta from the uterus. Patients with abruptio placentae typically present with bleeding, uterine contractions, and fetal distress. A significant cause of third-trimester bleeding associated with both fetal and maternal morbidity and mortality, abruptio placentae must be considered whenever bleeding is encountered in the second half of pregnancy.

Pathophysiology

Hemorrhage into the decidua basalis occurs as the placenta separates from the uterus. Vaginal bleeding usually follows, although the presence of a concealed hemorrhage in which the blood pools behind the placenta is possible.

If the bleeding continues, fetal and maternal distress may develop. Fetal and maternal death may occur if appropriate interventions are not undertaken. The primary cause of placental abruption is usually unknown, but multiple risk factors have been identified.

Frequency

United States

The frequency of abruptio placentae in the United States is approximately 1%, and a severe abruption leading to fetal death occurs in 0.12% of pregnancies (1:830).

Mortality/Morbidity

Maternal or fetal mortality or morbidity may occur.

If an abruption occurs, the risk of perinatal mortality is reported as 119 per 1,000 people in the United States, but this can depend on the extent of the abruption and the gestational age of the fetus. This rate is higher in patients with a significant smoking history. Fetal morbidity is caused by the insult of the abruption itself and by issues related to prematurity when early delivery is required to alleviate maternal or fetal distress.

Currently, placental abruption is responsible for approximately 6% of maternal deaths. Maternal and fetal complications include issues related to (1) cesarean delivery, (2) hemorrhage/coagulopathy, and (3) prematurity, described as follows:

• Cesarean delivery: Cesarean delivery is often necessary if the patient is far from her delivery date or if significant fetal compromise develops. If significant placental separation is present, the fetal heart rate tracing typically shows evidence of fetal decelerations and even persistent fetal bradycardia. A cesarean delivery may be complicated by infection, additional hemorrhage, the need for transfusion of blood products, injury of the maternal bowel or bladder, and/or hysterectomy for uncontrollable hemorrhage. In rare cases, death occurs.
• Hemorrhage/coagulopathy: Disseminated intravascular coagulation (DIC) may occur as a sequela of placental abruption. Patients with a placental abruption are at higher risk of developing a coagulopathic state than those with placental previa. The coagulopathy must be corrected to ensure adequate hemostasis in the case of a cesarean delivery.
• Prematurity: Delivery is required in cases of severe abruption or when significant fetal or maternal distress occurs, even in the setting of profound prematurity. In some cases, immediate delivery is the only option, even before the administration of corticosteroid therapy in these premature infants. All other problems and complications associated with a premature infant are also possible.

Race

Placental abruption is more common in African American women than in either white or Latin American women. However, whether this is the result of socioeconomic, genetic, or combined factors remains unclear.

Sex

This condition is observed only in pregnancy.

Age

An increased risk of placental abruption has been demonstrated in patients younger than 20 years and those older than 35 years.

Clinical

History

Symptoms may include vaginal bleeding, contractions, abdominal tenderness, and decreased fetal movement. Eliciting any history of trauma, such as assault, abuse, or motor vehicle accident, is important. A quick review of the patient's prenatal course, such as a known history of placenta previa, may help lead to the correct diagnosis. The patient should also be asked if she has had a placental abruption in a previous pregnancy. Questioning the patient about cocaine abuse, hypertension, trauma, or tobacco abuse is also crucial.

• Vaginal bleeding
  • Vaginal bleeding is present in 80% of patients diagnosed with placental abruptions.
  • Bleeding may be significant enough to jeopardize both fetal and maternal health in a relatively short period.
  • Remember that 20% of abruptions are associated with a concealed hemorrhage and the absence of vaginal bleeding does not exclude a diagnosis of abruptio placentae.
• Contractions/uterine tenderness
  • Contractions and uterine hypertonus are part of the classic triad observed with placental abruption.
  • Uterine activity is a sensitive marker of abruption and, in the absence of vaginal bleeding, should suggest the possibility of an abruption, especially after some form of trauma or in a patient with multiple risk factors.
• Decreased fetal movement
  • This may be the presenting complaint.
  • Decreased fetal movement may be due to fetal jeopardy or death.

Physical

The physical examination of a patient who is bleeding must be targeted at determining the origin of the hemorrhage. Simultaneously, the patient must be stabilized quickly. With placental abruption, a relatively stable patient may rapidly progress to a state of hypovolemic shock.

• Vaginal bleeding
  • Bleeding may be profuse and come in "waves" as the patient's uterus contracts.
  • A fluid the color of port wine may be observed when the membranes are ruptured.
• Contractions/uterine tenderness
  • Uterine contractions are a common finding with placental abruption.
  • Contractions progress as the abruption expands, and uterine hypertonus may be noted.
  • Contractions are painful and palpable.
  • Uterine hyperstimulation may occur with little or no break in uterine activity between contractions.
• Shock
  • Patients may present with hypovolemic shock, with or without vaginal bleeding, because a concealed hemorrhage may be present.
  • As with any hypovolemic condition, blood pressure drops as the pulse increases, urine output falls, and the patient progresses from an alert to an obtunded state as the condition worsens.
• Absence of fetal heart sounds: This occurs when the abruption progresses to the point that the fetus dies.
• Signs of possible fetal jeopardy
  • Fetal bradycardia is prolonged.
  • Repetitive, late decelerations are present.
  • Short-term variability is decreased.
• Fundal height: This may increase rapidly because of an expanding intrauterine hematoma.
• Important note: Do not perform a digital examination on a pregnant patient with vaginal bleeding without first ascertaining the location of the placenta. Before a pelvic examination can be safely performed, an ultrasonographic examination should be performed to exclude placenta previa. If placenta previa is present, a pelvic examination, either with a speculum or with bimanual examination, may initiate profuse bleeding.

Causes

While multiple risk factors are associated with abruptio placentae, only a few events have been closely linked to this condition, including the following:

• Cigarette smoking/tobacco abuse
  • Cigarette smoking increases a patient's overall risk of placental abruption.
  • A prospective cohort study showed the risk of abruption to be increased by 40% for each year of smoking prior to pregnancy.
  • In addition to the increased risk of abruption caused by tobacco abuse, the perinatal mortality rate of infants born to women who smoke and have an abruption is increased.
• Cocaine (powder or crack) 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. However, this hypothesis has not been definitively proven.
  • The rate of abruption in patients who abuse cocaine has been reported to be approximately 13-35% and may be dose-dependent.
• Trauma
  • Abdominal trauma is a major risk factor for placental abruption.
  • Motor vehicle accidents often cause abdominal trauma. The lower seat belt should extend across the pelvis, not across the mid abdomen, where the fetus is located.
  • Trauma may also be due to domestic abuse or assault, both of which are underreported.
• Thrombophilia
  • 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.
  • Note, however, that other literature does not support an association between thrombophilias and placental abruption. If a patient with a placental abruption is screened and is positive for a thrombophilia she should be offered treatment with heparin and aspirin during the next pregnancy.
• Other notable risk factors include the following:
  • Previous placental abruption
  • Chorioamnionitis
  • Prolonged rupture of membranes (24 h or longer)
  • Preeclampsia
  • Hypertension
  • Maternal age of 35 years or older
  • Male fetal sex
  • Low socioeconomic status
  • Elevated second trimester maternal serum alpha-fetoprotein (associated with up to a 10-fold increased risk of abruption)

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