In abruptio placentae, also called placental abruption, the placenta separates from the uterine wall prematurely, usually after the 20th week of gestation, producing hemorrhage. Abruptio placentae is a common cause of bleeding during the second half of pregnancy. Firm diagnosis, in the presence of heavy maternal bleeding, may necessitate termination of pregnancy. Fetal prognosis depends on the gestational age and amount of blood lost; maternal prognosis is good if hemorrhage can be controlled.
The cause of abruptio placentae is often unknown. Predisposing factors include trauma, such as a direct blow to the uterus, placental site bleeding from a needle puncture during amniocentesis, chronic or pregnancy-induced hypertension (which raises pressure on the placenta’s maternal side), multiparity, smoking, and cocaine abuse.
In abruptio placentae, blood vessels at the placental bed rupture spontaneously owing to a lack of resiliency or to abnormal changes in uterine vasculature. Hypertension complicates the situation, as does an enlarged uterus, which can’t contract sufficiently to seal off the torn vessels. Consequently, bleeding continues unchecked, possibly shearing off the placenta partially or completely. Typically, such bleeding is external or marginal (in about 80% of patients) if a peripheral portion of the placenta separates from the uterine wall; it is internal or concealed (in about 20%) if the central portion of the placenta becomes detached and the still-intact peripheral portions trap the blood. As blood enters the muscle fibers, complete relaxation of the uterus becomes impossible, increasing uterine tone and irritability. If bleeding into the muscle fibers is profuse, the uterus turns blue or purple, and the accumulated blood prevents its normal contractions after delivery (Couvelaire uterus, or uteroplacental apoplexy).
Abruptio placentae produces a wide range of clinical effects, depending on the extent of placental separation and the amount of blood lost from maternal circulation. (See Degrees of placental separation in abruptio placentae, page 968.) Mild abruptio placentae (marginal separation) develops gradually and produces mild to moderate bleeding, vague lower abdominal discomfort, mild to moderate abdominal tenderness, and uterine irritability. Fetal heart tones remain strong and regular.
Moderate abruptio placentae (about 50% placental separation) may develop gradually or abruptly and produces continuous abdominal pain, moderate dark red vaginal bleeding, a tender uterus that remains firm between contractions, barely audible or irregular and bradycardiac fetal heart tones and, possibly, signs of shock. Labor usually starts within 2 hours and often proceeds rapidly.
Severe abruptio placentae (70% placental separation) develops abruptly and causes agonizing, unremitting uterine pain (described as tearing or knifelike); a boardlike, tender uterus; moderate vaginal bleeding; rapidly progressive shock; and absence of fetal heart tones.
In addition to hemorrhage and shock, complications of abruptio placentae may include renal failure, disseminated intravascular coagulation (DIC), and maternal and fetal death.
Diagnostic measures for abruptio placentae include observation of clinical features, speculum examination, and ultrasonography to rule out placenta previa. Decreased hemoglobin (Hb) levels and platelet counts support the diagnosis. Periodic assays for fibrin split products aid in monitoring the progression of abruptio placentae and detect the development of DIC.
Treatment of abruptio placentae is designed to assess, control, and restore the amount of blood lost; to deliver a viable infant; and to prevent coagulation disorders. Immediate measures for abruptio placentae include starting I.V. infusion (via large-bore catheter) of appropriate fluids (lactated Ringer’s solution) to combat hypovolemia; placement of a central venous pressure line and urinary catheter to monitor fluid status; drawing blood for Hb levels and hematocrit determination, for coagulation studies, and for type and crossmatching; external electronic fetal monitoring; and monitoring of maternal vital signs and vaginal bleeding.
After determination of the severity of abruption and appropriate fluid and blood replacement, prompt delivery by cesarean birth is necessary if the fetus is in distress. If the fetus isn’t in distress, monitoring continues; delivery is usually performed at the first sign of fetal distress. Because of possible fetal blood loss through the placenta, a pediatric team should be ready at delivery to assess and treat the neonate for shock, blood loss, and hypoxia. If placental separation is severe and there are no signs of fetal life, vaginal delivery may be performed unless uncontrolled hemorrhage or other complications contraindicate it.
Complications of abruptio placentae require appropriate treatment. For example, DIC requires immediate intervention with heparin, platelets, and whole blood to prevent exsanguination.
❑ Check maternal blood pressure, pulse rate, respirations, central venous pressure, intake and output, and amount of vaginal bleeding every 10 to 15 minutes. Monitor fetal heart tones electronically.
❑ Prepare the patient and her family for cesarean birth. Thoroughly explain postpartum care so the patient and her family will know what to expect.
❑ If vaginal delivery is elected, provide emotional support during labor. Because of the infant’s prematurity, the mother may not receive analgesics during labor and may experience intense pain. Reassure the patient of her progress through labor and keep her informed of the fetus’condition.
❑ Provide emotional support. In the case of fetal demise, encourage the patient to seek counseling as appropriate.
Read excerpts from these other book chapters related to Abruptio placentae:
Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2008 Williams & Wilkins.
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Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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