Excerpt from Abruptio Placentae

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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.

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