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

Epidemiology

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

Etiology

• 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

• 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

• 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

• 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

• 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