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Emergency And Acute Medicine – Placental Abruption
Placental abruption is hemorrhage at the decidual–placental interface resulting in partial or complete separation of a normally implanted placenta before delivery of the fetus. It occurs in approximately 1% of all pregnancies and accounts for about 30% of bleeding episodes in the second half of pregnancy. It is responsible for 15% of fetal deaths, with neonatal mortality rates of 10–30%, and contributes to approximately 6% of maternal mortality. It is also referred to as abruptio placentae or accidental hemorrhage.
The primary cause is unknown, but the underlying process involves vascular injury with bleeding into the decidua basalis or mechanical shearing between the placenta and uterus, leading to clot formation and placental separation. Severe cases may result in disseminated intravascular coagulation (DIC) and significant maternal–fetal compromise. Many abruptions are thought to arise from chronic inflammatory or ischemic placental disease. Acute abruption may occur following trauma, rapid uterine decompression, or implantation over a uterine anomaly or fibroid.
Risk factors include prior abruption (10–20% recurrence risk), maternal hypertension and preeclampsia, advanced maternal age, increased parity, multiple gestation, uterine fibroids, tobacco use, cocaine abuse, trauma, premature rupture of membranes, oligohydramnios, polyhydramnios with rapid decompression, rapid delivery of the first twin, elevated second-trimester maternal serum alpha-fetoprotein, and thrombophilias. It is more common among African American and Caucasian women, with incidence increasing more rapidly among African American women.
Patients typically present after 20 weeks’ gestation with vaginal bleeding, which is painful in more than 80% of cases. However, bleeding may be absent in 20–25% due to concealed hemorrhage. Abdominal or back pain, uterine tenderness, frequent contractions, uterine tetany, nausea, vomiting, and unexplained preterm labor may occur. A history of trauma or cocaine use should be sought. On examination, uterine tenderness is common, and signs of hypotensive shock may appear late. Fetal distress may manifest as decreased fetal movement, bradycardia, or nonreassuring fetal heart rate tracings. Signs of DIC such as petechiae or bleeding from IV sites may be present. A sterile vaginal examination must be performed cautiously, particularly if placenta previa has not been excluded.
Diagnosis is primarily clinical. Immediate evaluation includes large-bore IV access, blood type and cross-match, rapid hemoglobin assessment, and continuous fetal and uterine monitoring. Laboratory studies include CBC, PT/PTT, fibrinogen level, and fibrin split products. Fibrinogen levels below 200 mg/dL and platelets below 100,000/μL strongly suggest abruption with coagulopathy. Kleihauer–Betke testing is indicated in Rh-negative patients. Ultrasound identifies abruption in only about 50% of cases, and a negative study does not exclude the diagnosis. MRI is sensitive but not practical in acute settings. CT performed for trauma evaluation may incidentally reveal abruption.
The differential diagnosis includes placenta previa, uterine rupture, preterm labor, vaginal or cervical lacerations, ovarian torsion, pyelonephritis, cholecystitis, appendicitis, and other intra-abdominal trauma.
Prehospital management includes transport in the left lateral recumbent position with full resuscitative measures if shock is suspected. Initial stabilization focuses on airway, breathing, and circulation with oxygen, cardiac monitoring, large-bore IV access, and aggressive crystalloid resuscitation. In the emergency department, continuous maternal cardiac and fetal monitoring is required. Blood products including packed red blood cells, fresh frozen plasma, cryoprecipitate, and platelets should be administered as indicated, often via a massive transfusion protocol. Immediate obstetric consultation is mandatory. Foley catheter placement allows close urine output monitoring. Tocolysis is generally contraindicated. In trauma-associated abruption, maternal stabilization takes priority.
Rh-immunoglobulin (300 μg IM at ≥12 weeks’ gestation) should be administered to Rh-negative patients, with dosing adjusted based on Kleihauer–Betke results. Corticosteroids for fetal lung maturity between 24 and 34 weeks and magnesium sulfate may be considered in consultation with obstetrics.
All confirmed or suspected cases require admission for maternal and fetal monitoring. ICU care is indicated for DIC, amniotic fluid embolism, or severe hemorrhage. Stable trauma patients without evidence of abruption after 4–6 hours of normal monitoring may be discharged in consultation with obstetrics, with instructions for pelvic rest and close follow-up.
Placental abruption remains a clinical diagnosis, as no single test reliably confirms or excludes it. Hypotension is often a late finding in pregnant patients with hypovolemia. Early anticipation of consumptive coagulopathy and prompt blood product administration are critical. Severe preeclampsia may mask hypovolemia, resulting in a normotensive but critically ill patient, and should be considered in any severe or unexplained abruption.
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