Placental Abruption - Pathophysiology

Pathophysiology

Trauma, hypertension, or coagulopathy contributes to the avulsion of the anchoring placental villi from the expanding lower uterine segment, which in turn, leads to bleeding into the decidua basalis. This can push the placenta away from the uterus and cause further bleeding. Bleeding through the vagina, called overt or external bleeding, occurs 80% of the time, though sometimes the blood will pool behind the placenta, known as concealed or internal placental abruption.

Women may present with vaginal bleeding, abdominal or back pain, abnormal or premature contractions, fetal distress or death.

Abruptions are classified according to severity in the following manner:

• Grade 0: Asymptomatic and only diagnosed through post partum examination of the placenta.
• Grade 1: The mother may have vaginal bleeding with mild uterine tenderness or tetany, but there is no distress of mother or fetus.
• Grade 2: The mother is symptomatic but not in shock. There is some evidence of fetal distress can be found with fetal heart rate monitoring.
• Grade 3: Severe bleeding (which may be occult) leads to maternal shock and fetal death. There may be maternal disseminated intravascular coagulation. Blood may force its way through the uterine wall into the serosa, a condition known as Couvelaire uterus.