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Obstetrics and Gynecology/Hemorrhage in the Late Third Trimester and Parturition

< Obstetrics and Gynecology

Epidemiology

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  • 5% of pregnancies are affected by hemorrhage, and 10% of maternal deaths in the developed world are the result of bleeding.

Etiology

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  • Abruption of the placenta (prematue separation of the placenta from the uterine wall)
    • Complicates 1% of pregnancies and is the major cause of antepartum bleeding.
    • These are very difficult to identify and diagnose.
    • May be caused by trauma, cocaine use, and sudden uterine decompression. Smoking, hypertension, and history of previous placental abruption increase the risk of future abruption.
  • Placenta previa
    • Placenta covering or in close proximity to the internal cervical canal.
    • Placenta previa is responsible for approximately 20% of bleeding in late pregnancy; less than abruption of the placenta.
    • 0.5% of pregnancies will be affected at term. Some may start as previa but migrate away from the cervix with pregnancy.
    • Risk increases with previous placenta previa, cesarian section, advancing maternal age, multiparity, smoking, and prior abortions.
  • Uterine rupture
  • Vasa previa
  • Lower genital tract bleeding from laceration, iatrogenesis, cervical cancer.
  • Gastointestinal or urinary tract bleeding confused with genital bleeding.
  • Placental morphology may facilitate bleeding.

Pathophysiology

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  • Placental abruption: hemorrhage into the basal decidua of the placenta, coupled with uterine contractions leads to placental separation. Further hemorrhage exacerbates prostaglandin formation and separation of the placenta.
  • Placenta previa: bleeding can create abruption.

Clinical Presentation

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  • Abruption of the placenta
    • Bleeding
    • Cramps/pain
    • Absent contractions
    • Non-reassuring fetal heart rate
  • Placenta previa
    • Will usually present initially with an asymptomatic bleed that resolves spontaneously.
    • Diagnosis must be made by transvaginal ultrasound.
    • Make sure that it is not vasa previa: test nucleated blood cells with a sodium hydroxide dilution test.

Complications

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  • Abruption of the placenta
    • Hypovolemia
    • Post-partum pituitary insufficiency (Sheehan's syndrome)
    • ARDS
    • Cardiac arrest
    • Fetal death (11% in developed countries)
    • Prematurity/intrauterine growth retardation

Management

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  • Abruption of the placenta
    • ABC's, hemodynamic stability
    • Prep for operating room
    • Blood transfusion and or clotting factor replacement
    • Rapid exsanguination indicates cesarian section and hysterectomy; stable bleeding indicates delivery; mild bleeding indicates conservative observation with steroids for fetal lung development.
  • Placenta previa
    • ABC's and hemodynamic stability
    • Cesarian section unless unviable pregnancy
    • There is a risk of fetal hemorrhage and perinatal mortality of >10%.
    • Stable with ongoing bleeding: admission, tocolysis for contractile cessation, and steroids for fetal development
    • Unstable mother or fetus: cesarian section unless nonviable
    • No hemorrhage warrants assessment of fetal lung function
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