DEFINITION
Placental abruption is defined as premature separation of a normally implanted placenta. Although some de- gree of placental separation often occurs when there is a placenta previa, these cases are not conventionally con- sidered abruptions in the true sense. Abruption may be “revealed,” in which case blood tracks between the membranes and the decidua, and escapes through the cervix into the vagina (Fig. 1A). The less common “concealed” abruption occurs when blood accumulates behind the placenta, with no obvious external bleeding (Fig. 1B). Finally, abruption may be total, involving the entire placenta, in which case it typically leads to fetal death, or partial, with only a portion of the placenta detached from the uterine wall.