Abruptio Placentae

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:

• In the US: 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.

Treatment
Medical Care: Inpatient admission is required if abruptio placentae is considered likely.

• Procedures

• Obtain intravenous access using 2 large-bore intravenous lines.
• Institute crystalloid fluid resuscitation for the patient.
• Type and crossmatch blood.
• Begin a transfusion if the patient is hemodynamically unstable after fluid resuscitation.

• Correct coagulopathy, if present.

• Administer Rh immune globulin if the patient is Rh-negative.

• Vaginal delivery

• This is the preferred method of delivery for a fetus that has died secondary to placental abruption.
• The ability of the patient to undergo vaginal delivery depends on her remaining hemodynamically stable.
• Delivery is usually rapid in these patients secondary to increased uterine tone and contractions.

Surgical Care:

• Cesarean delivery

• Cesarean delivery is often necessary for both fetal and maternal stabilization.

• While cesarean delivery facilitates rapid delivery and direct access to the uterus and its vasculature, it can be complicated by the patient's coagulation status. Because of this, a vertical skin incision, which has been associated with less blood loss, is often used when the patient appears to have DIC.

• The type of uterine incision is dictated by the gestational age of the fetus, with a vertical or classic uterine incision often being necessary in the preterm patient.

• If hemorrhage cannot be controlled after delivery, a cesarean hysterectomy may be required to save the patient's life.

• Before proceeding to hysterectomy, other procedures, including correction of coagulopathy, ligation of the uterine artery, administration of uterotonics (if atony is present), packing of the uterus, and other techniques to control hemorrhage, may be attempted.

• ICU: If the patient is hemodynamically unstable, either before or after delivery, invasive monitoring in an ICU may be required.

Consultations:

• Maternal-fetal medicine specialist

• If a mild abruption is diagnosed or the diagnosis is questionable, a maternal-fetal medicine (MFM) specialist should be consulted.

• In the case of a preterm fetus in which tocolysis is considered likely, consulting an MFM specialist may be prudent.

• Pediatricians or neonatal intensive care specialists should be consulted if the fetus is considered viable, usually at 24 weeks' gestation, and delivery is anticipated.

Diet:

• The patient should be restricted to nothing by mouth (NPO) if emergent delivery is a possibility.

Activity:

• Preterm patients diagnosed with a chronic abruption may be started on a modified bedrest regimen and monitored closely for any signs of maternal or fetal distress that could necessitate delivery. Again, consultation with MFM specialists is advised for conservative management of abruptio placentae.

Medication
Tocolysis is considered controversial in the management of placental abruption and is considered only in patients (1) who are hemodynamically stable, (2) in whom no evidence of fetal jeopardy exists, and (3) in whom a preterm fetus may benefit from corticosteroids or delay of delivery.

Even in patients meeting these criteria, consultation with an MFM specialist is important. Tocolysis must be undertaken with caution because maternal or fetal distress can develop rapidly. In general, magnesium sulfate is used for tocolysis and beta-sympathomimetic agents are avoided, as the latter may cause significant undesirable cardiovascular effects, such as tachycardia, which may mask clinical signs of blood loss in these patients.

Drug Category: Tocolytics -- May allow for effective administration of glucocorticoids to the preterm fetus to accelerate fetal lung maturation. In chronic abruption, may also help delay delivery to a gestational age when complications of prematurity are less severe.

Drug Name	Magnesium sulfate -- DOC for tocolysis in patients with placental abruption.
Adult Dose	Initial dose: 4-6 g IV bolus over 20 min Maintenance dose: 2-4 g/h IV, titrated prn to suppress contractions
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity; hypocalcemia; myasthenia gravis, renal failure
Interactions	Concurrent use with nifedipine may cause hypotension and neuromuscular blockade; may increase neuromuscular blockade noted with aminoglycosides and potentiate neuromuscular blockade produced by tubocurarine, vecuronium, and succinylcholine; may increase CNS effects and toxicity of CNS depressants and betamethasone and cardiotoxicity of ritodrine
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Adverse effects include flushing, blurry vision, headaches, and nausea; more serious adverse effects, observed only at toxic levels, include pulmonary edema, respiratory depression, cardiac arrest, maternal tetany, and profound hypotension; to reverse effects, calcium gluconate (1 g slow IV push) may be administered