Placental Abruption

Basics

Description

  • Hemorrhage at the decidual–placental interface leading to complete or partial separation of the placenta before delivery of the fetus
  • Incidence/prevalence:
    • ∼1% of all pregnancies
    • 30% of bleeding episodes in the second half of pregnancy
    • Associated with a 20-fold increase in perinatal death (from 0.6–12% in the case of placental abruption)
  • Classification:
    • By presence or absence of vaginal bleeding:
      • Revealed (vaginal bleeding present, 65–80% of cases)
      • Concealed (vaginal bleeding absent, 20–35% of cases)
    • By amount of placental separation:
      • Partial (only part of placenta detached, 93% of cases)
      • Total or complete (entire placenta detached, 7% of cases)
    • By severity:
      • Grade 0 – asymptomatic
      • Grade 1 – no signs of maternal or fetal distress
      • Grade 2 – no signs of maternal distress/shock but fetal distress is present
      • Grade 3 – maternal shock, fetal distress, or death
  • Synonym(s): Abruptio placentae, placenta abruption, ablation placentae, accidental hemorrhage (in the UK)

Etiology

  • Hemorrhage of a maternal artery or vein causing bleeding at the decidual–placental interface leading to premature placental separation
  • Inciting event may be unclear
  • The majority of abruptions are due to chronic processes:
    • Inflammatory changes in the placenta
    • Manifestation of ischemic placental disease
    • Defective trophoblastic implantation
  • Acute abruption can occur due to:
    • Trauma
    • Rapid uterine decompression
    • Placenta implantation over a uterine anomaly or fibroid
  • Multiple known risk factors:
    • Previous abruption (10–20% recurrence risk)
    • Maternal hypertension (>140/90) and pre-eclampsia
    • Increased parity and maternal age
    • Multiple gestation
    • Fibroids or other uterine/placental abnormalities
    • Tobacco use
    • Cocaine abuse
    • Trauma
    • Premature rupture of membranes, particularly if associated with chorioamnionitis or oligohydramnios
    • Rapid uterine decompression:
      • Polyhydramnios with membrane rupture
      • Rapid delivery of first twin
    • Elevated second trimester maternal serum α-fetoprotein
    • Thrombophilias
    • First or second trimester vaginal bleeding
    • Maternal race:
      • More common among African American and Caucasian women
      • Incidence increasing more rapidly among African American women

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