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Third-trimester bleeding occurs in 4% of all pregnancies. In 50% of cases, vaginal bleeding is secondary to placental abruption or placenta previa.
Clinical Evaluation of Late-pregnancy Bleeding
History of trauma or pain, and the amount and character of the bleeding are assessed.
Vital signs and pulse pressure are measured. Hypotension and tachycardia are signs of serious hypovolemia.
Fetal heart rate pattern and
Placental abruption (abruptio placentae) is defined as complete or partial placental separation from the decidua basalis after 20 weeks gestation.
Placental abruption occurs in 1 in 100 deliveries.
Factors Associated with Placental Abruption
Preeclampsia and hypertensive disorders
History of placental abruption
High multiparity
Increasing maternal age
Trauma
Cigarette smoking
Illicit drug use (especially cocaine)
Excessive alcohol consumption
Preterm premature rupture of the membranes
Rapid uterine decompression after delivery of the first fetus in a twin gestation or rupture of membranes with polyhydramnios
Uterine leiomyomas
Diagnosis of Placental Abruption
1. Abruption is characterized by vaginal bleeding, abdominal pain, uterine tenderness, and uterine contractions.
a. Vaginal bleeding is visible in 80%; bleeding is concealed in 20%.
b. Pain is usually of sudden onset, constant, and localized to the uterus and lower back.
c. Localized or generalized uterine tenderness and increased uterine tone are found with severe placental abruption.
d. An increase in uterine size may occur with placental abruption when the bleeding is concealed, and it may be detected by serial measurements of abdominal girth and fundal height.
e. Amniotic fluid may be bloody.
f. Fetal monitoring may detect distress.
g. Placental abruption may cause preterm labor.
2. Uterine contractions by tocodynamometry third-trimester bleeding, pregnancy, bleeding is the most sensitive indicator of abruption.
3. Laboratory Findings include proteinuria and a consumptive coagulopathy, characterized by decreased fibrinogen, prothrombin, factors V and VIII, and platelets. Fibrin split products are elevated.
4. Ultrasonography. The sensitivity of ultrasonography in detecting placental abruption is only 15%.
Management of Placental Abruption